UNIVERSITY    OF   CALIFORNIA 

COLLEGE    OF    AGRICULTURE 

AGRICULTURAL   EXPERIMENT   STATION 

CIRCULAR  No.  279 
October,  1924 

THE  PREPARATION  AND  REFINING  OF 
OLIVE  OIL  IN  SOUTHERN  EUROPE 

By  W.  V.  CRUESS 


INTRODUCTION 

Olive  oil  has  been  used  by  southern  European  peoples  as  an 
important  food  since  the  beginning  of  historical  time.  Large  areas 
in  Spain,  Italy,  France,  Greece,  and  other  Mediterranean  countries  are 
planted  with  olives,  while  the  preparation  and  refining  of  olive  oil  are 
basic  industries  in  these  countries. 

This  publication  has  been  prepared  as  a  report  upon  observations 
made  during  a  recent  visit  to  tfie  olive  oil  producing  and  refining 
centers  of  Spain,  France,  and  Italy. 

The  attainment  of  the  objects  of  this  visit  was  greatly  facilitated 
by  information  and  assistance  generously  furnished  by  various  indi- 
viduals and  firms.  In  Spain  by  W.  C.  Burdette,  American  Consul, 
and  Francisco  Martin,  American  Vice-consul  at  Seville ;  Ernesto  Peter 
of  Seville;  the  Union  Oliverera  of  Carmona;  R.  Sala  of  Balaguer; 
Dr.  August  Matons,  University  of  Barcelona;  Don  Isidoro  Aguilo, 
Director  of  the  Olive  Experiment  Station  of  Tortosa;  R.  J.  Totten, 
American  Consul  General,  Barcelona.  In  France  by  L.  Frost,  Amer- 
ican Consul  General,  Marseilles ;  Victor  Coq  et  Fils,  machinery  manu- 
facturers of  Aix-en-Provence.  In  Italy  by  Professor  Asher  Hobson, 
Dr.  Trinchieri,  and  others  of  the  International  Institute  of  Agricul- 
ture, Rome ;  Commendatore  Casardi,  Florence ;  and  by  F.  Bertolli  of 
Lucca  and  New  York. 

The  California  Ripe  Olive  Association  defrayed  part  of  the  expense 
of  the  trip,  for  which  due  acknowledgment  is  made. 

It  is  believed  that  the  information  collected  and  presented  here 
will  be  of  interest  to  the  olive  oil  manufacturers  of  California,  and 
of  value  in  improving  the  quality  of  California  oil. 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


GENERAL  STATUS  OF  THE  OLIVE   OIL  INDUSTRY  IN  EUROPE 

Although  olive  oil  is  a  staple  food  product  in  southern  Europe,  its 
producers  are  not  at  present  in  a  very  prosperous  condition. 

1.  Production. — According  to  Dore*  the  acreages  of  olives  for  the 
various  Mediterranean  countries  were  in  1911  and  1922  as  shown  in 
table  1.  It  is  believed  that  Dore's  figures  are  more  accurate  than  those 
published  by  other  agencies  because  his  data  were  secured  through  the 
International  Institute  of  Agriculture,  which  has  unusually  good 
facilities  for  gathering  such  statistics. 


TABLE  1 

Acreage  of  Olives  in  Mediterranean  Countries 
(After  Dore) 


Country 

France 

Greece 

Italy 

Portugal 

Spain 

Algeria 

Tunis 


Area  in  olives,  1911 
(in  acres) 


Area  in  olives,  1922 


No  data 
252,566 
5,700,000 
No  data 
3,567,327 
No  data 
No  data 


296,500 

No  data 
5,659,000 

815,500  (in  1920) 
4,102,185 
85,623 
575,888 


The  production  of  oil  varies  greatly  from  year  to  year  as  shown 
by  the  data  in  table  2,  taken  from  Dore's  report.    See  table  2,  page  3. 

The  total  production  for  1921  was  550,466  long  tons  or  161,186,500 
gallons;  or  52,680,100  gallons  (about  25  per  cent)  less  than  in  1922. 
In  most  of  the  above  countries  a  year  of  heavy  production  is  followed 
by  one  of  light  production ;  e.g.,  the  production  in  long  tons  for  Italy 
for  the  years  1918,  1919,  1920,  1921,  and  1922  respectively  were 
256,000,  101,100,  180,600,  143,100,  and  236,200.  Nevertheless  the 
total  production  for  the  whole  Mediterranean  region  is  fairly  constant. 

The  production  per  acre  in  Italy  is  lower  than  in  France  and 
Spain  because  mixed  plantings  and  intercropping  are  more  common 
in  Italy.    See  also  page  9. 

2.  General  Economic  Conditions  of  the  Industry. — The  manufac- 
turers of  olive  oil  in  the  countries  visited  complained  that  the  cost 
of  production  of  oil  has  increased  in  recent  years  out  of  proportion 
to  the  selling  price — and  that  consequently  the  net  returns  are  small. 

*  Dore,  Valentino.  Oleaginous  Products  and  Vegetable  Oils,  Production  and 
Trade.  Published  by  the  International  Institute  of  Agriculture,  Villa  Borghesi, 
Borne,  1923. 


Circular  279] 


OLIVE    OIL    IN    SOUTHERN    EUROPE 


3 


(a)  Spain. — While  Spain  produces  more  olive  oil  than  any  country 
in  the  world,  her  oils  are  not  so  well  known  in  other  countries  as  those 
of  Italy  and  France.  However,  it  is  a  recognized  fact  that  much  of 
the  Italian  and  French  oil,  particularly  that  for  export,  consists  of 
blends  containing  a  large  proportion  of  fine  Spanish  oil. 


TABLE  2 

Production  of  Olive  Oil  in  Mediterranean  Countries 

(After  Dore) 


*  France — after  J.  Bonnet  La  Culture  de  l'Olivier. 

The  probable  cause  for  this  situation  has  been  the  more  rapid 
progress  made  in  Italy  and  France  in  the  refining,  blending,  packag- 
ing, and  foreign  marketing  of  oil.  The  refiners  of  Marseilles,  Genoa, 
the  Lucca  district,  etc.,  have  in  the  past  offered  attractive  prices  for 
the  finer  grades  of  Spanish  oil,  leaving  for  the  Spanish  export  markets 
principally  inferior  grades.  Thus,  the  Spanish  labels  have  come  more 
or  less  into  disrepute  and  the  French  and  Italian  oils  have  become 
firmly  established  in  the  North  and  South  American  markets  and 
elseAvhere. 

In  recent  years,  Spain  has  made  great  progress  in  oil  making  and 
refining.  She  now  possesses  modern  mills  and  up-to-date  refineries. 
(See  figure  1.)  As  a  result,  the  average  quality  of  her  oils  has  been 
greatly  improved  and  her  fine  oils  rank  with  the  best  of  Italy  and 
France.  The  difficulty  has  been  to  convince  consumers  and  dealers 
of  this  fact.  Consequently  large  quantities  of  Spanish  oil  are  still 
exported  to  Marseilles,  Genoa,  and  other  foreign  refining  centers  for 
blending  purposes. 


4  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

The  Spanish  refiners  and  oil  manufacturers  are  not  well  organized ; 
there  has  therefore  been  very  little  cooperative  effort  in  attempting 
to  develop  foreign  markets. 

It  must  be  remembered  that  the  Spanish  currency  has  not  depre- 
ciated nearly  so  much  as  the  French  and  Italian.  At  the  time  of  the 
writer's  visit,  the  Spanish  peseta  was  equivalent  to  14c  American,  the 
French  franc  to  4%c  and  the  Italian  lira  to  414c.  At  par,  each  of  these 
is  equivalent  to  about  20c  American.  This  disparity  in  value  has 
given  the  French  and  Italian  dealers  a  great  price  advantage  over  the 


Fig.  1. — Upper,  new  building  of  Union  Oliverera  oil  factory,  Carmona, 
Spain.    Lower,  oil  refinery,  Italy. 

Spanish  dealers,  because  production  costs  have  not  increased  in  France 
and  Italy  in  proportion  to  the  fall  in  value  of  the  currency.  France 
and  Italy,  it  is  said,  are  buying  an  increasing  amount  of  oil  from 
Algiers  and  Tunis  because  the  relatively  high  value  of  the  peseta 
causes  the  Spanish  oil  tc  be  higher  in  price  than  the  North  African 
oils.  Thus,  the  Spanish  producer  is  in  a  rather  desperate  marketing 
situation. 

During  the  war,  Spain  had  an  excellent  opportunity  to  develop 
export  markets,  because  France  and  Italy  were  otherwise  occupied. 
The  Spanish  Government  for  a  time  fostered  this  development  but  in 
1918  became  alarmed  at  the  increasing  exportation  and  placed  an 
embargo  on  exports  in  order  to  protect  the  domestic  supply.     This 


Circular  279]  OLIVE   OIL   IN   SOUTHERN   EUROPE  5 

embargo  proved  fatal  to  further  expansion  of  Spanish  export  markets 
for  the  reason  that  the  war  closed  in  1918  and  France  and  Italy  again 
entered  the  world  markets  before  Spanish  exporters  could  recover 
from  the  effects  of  the  embargo. 

In  November,  1923,  Spanish  oil  refineries  and  factories  had  on 
hand  a  large  surplus  of  oil  from,  the  previous  season,  produced  at  high 
prices  and  salable  only  on  a  falling  market.  The  tendency  appeared 
to  be  to  hold  the  oil  and  to  refuse  to  sell  except  at  prices  that  would 
at  least  return  the  wartime  production  cost.  American  Consul 
Burdette  of  Seville  recommended  sale  at  world  market  prices  of  this 
"hold  over"  oil  even  at  a  loss  in  order  to  reestablish  Spanish  oil  in 
export  markets  and  assure  future  markets  for  the  oil. 

(b)  France. — France  does  not  produce  enough  olive  oil  for  its  own 
needs.  Consequently  much  oil  is  imported,  largely  by  Marseilles,  for 
refining  and  blending.  During  the  war,  peanut  oil  was  blended  with 
olive  oil  to  replace  imported  olive  oils  (unobtainable  in  sufficient 
quantity  at  that  time).  The  blend  was  well  received  and  became 
popular.  According  to  refiners  and  dealers  interviewed  in  Marseilles, 
the  use  of  this  "table  oil"  blend,  consisting  of  about  75  per  cent  pea- 
nut oil  and  25  per  cent  olive  oil,  is  increasing — so  that  France  is 
becoming  less  dependent  upon  imported  olive  oil. 

In  Spain  the  olive  industry  is  expanding — in  France,  on  the  other 
hand,  according  to  J.  Bonnet,  Director  of  the  Olive  Service  of  France, 
the  area  planted  with  olives  is  decreasing  because  olives  give  a  smaller 
return  to  the  grower  than  do  some  other  crops.  The  substitution  of 
peanut  oil  for  olive  oil  at  a  price  much  below  that  of  olive  oil  is  also 
a  factor. 

(c)  Italy.- — The  Italian  grower  is  usually  also  an  oil  maker  and 
sells  oil  rather  than  fruit — in  this  respect  differing  somewhat  from  the 
French  and  Spanish  growers.  Figure  2  illustrates  a  typical  farmer's 
oil  factory  building.  He  produces  most  of  his  other  necessary  food, 
such  as  wheat,  vegetables,  etc.,  and  is  usually  not  so  dependent  upon 
the  return  from  his  olives  as  is  the  grower  in  some  other  countries. 
Farm  and  olive  factory  labor  costs  have  not  risen  so  high  as  in  France 
and  Spain — consequently  the  Italian  oil  maker  can  produce  more 
cheaply  than  his  Spanish  and  French  competitors.  For  these  reasons 
the  Italian  growers  of  oil  olives  and  the  refiners,  as  well,  appear  to  be 
in  a  better  position  economically  than  in  the  other  countries  visited. 

3.  Cooperative  Factories. — At  one  time  most  of  the  Spanish  and 
French  oils  were  made  in  small  factories  owned  and  operated  by 
individual  farmers.     This  is  still  true  of  manv  sections  of  Italv. 


6  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

In  recent  years  many  cooperatively  owned  factories  have  been 
erected,  particularly  in  northeastern  Spain  and  in  the  Marseilles- 
Nimes-Aix-en-Provence  area  of  southern  France.  Several  were 
visited.  In  all  cases  the  machinery  was  of  the  best  and  apparently 
the  plants  were  intelligently  operated.  The  cooperative  movement  is 
being  fostered  by  the  French  and  Spanish  governments.  Certain 
government  experts  assist  in  organizing  the  cooperatives,  and  others 
in  erecting,  equipping,  and  operating  the  plants. 

A  typical  cooperative  in  Tortosa  has  about  150  members,  many  of 
which  formerly  operated  small  mills.  The  olives  are  now  brought  to 
a  central  factory  in  Tortosa,  where  each  member's  olives  are  kept 
separate  and  the  yield  and  quality  of  the  oil  of  each  determined.    Pay- 


Fig.  2. — Small  olive  oil  factory  near  Florence,  Italy. 

ment  is  made  accordingly.  Cooperative  manufacture  has  improved 
the  average  quality  of  the  oil  and  cooperative  marketing  has  strength- 
ened the  growers'  marketing  position. 

In  southern  Spain  the  large  privately  owned  factory  and  the  indi- 
vidual grower's  mill,  rather  than  cooperatives  are  the  rule.  Probably 
the  system  of  holding  land  in  very  large  estates,  as  contrasted  with 
the  numerous  small  orchards  of  northern  Spain  and  southern  France 
account  for  this  difference  in  ownership  of  factories. 

4.  Costs. — While  the  costs  of  production  in  Spain,  France,  and 
Italy  have  increased  greatly  during  the  past  ten  years,  they  are  still 
considerably  less  than  in  California. 

(a)  Spain. — The  price  asked  for  oil  olives  in  Seville  in  October, 
1924,  was  15  pesetas  per  fanega  (about  $43.75  per  ton),  but  Consul 
Burdette  reported  that  the  average  price  paid  at  harvest  was  $28.30 
per  ton  (about  10  pesetas  per  fanega). 


Circular  279] 


OLIVE    OIL    IN    SOUTHERN    EUROPE 


A  report  by  the  Spanish  Government  in  1923  gives  the  cost  of 
growing  olives  and  making  oil  in  the  various  provinces.  The  following 
cost  sheet  for  Huelva  is  typical. 


TABLE  3* 
Cost  of  Growing  Olives  in  Huelva,  Spain  (1922) 


Item 


Cost  per 

hectare  of  land 

in  pesetas 


Cost  per  acre 


Pesetas 


Dollars 


Plowing 

Cross  plowing 

Cleaning 

Pruning 

Guarding 

Taxes 

Rent 

Harvesting 

Rolling 

Transporting 

Interest  on  capital 

Total 


32.00 
28.00 
16.00 

5.85 

7.50 

27.00 

120.00 

40.50 

9.00 
11.00 

9.80 


12.9 

11.4 

6.4 

2.4 

3.0 

10.9 

48.6 

16.5 

3.7 

4.4 

3.9 


1.80 

1.60 

.90 

.34 

.42 

1.52 

6.80 

2.31 

.52 

.62 

.54 


306.65 


124.1 


$17.37 


Yield:  19  quintals  of  olives,  4180  lbs.,  per  hectare,  or  about  1700 
lbs.  per  acre.    Cost,  16.14  pesetas  per  quintal,  or  $20.46  per  ton. 


TABLE  4 
Manufacturing  Cost — Province  of  Huelva,  Spain 


Item 


Cost  per 

quintal  of  oil, 

pesetas 


Cost  per 

gallon  of  oil, 

dollars 


Fixed  costs;  taxes,  insurance,  etc 

Power 

Wages,  2  mill  men  at  4  pstas 

Wages,  2  other  men  at  3.5  pstas.. 

Other  charges 

Olives,  6.25  quintals 

Crushing 

Total 


29.25 
12.00 
8.00 
7.00 
3.50 
100.87 
4.06 


166.68 


$0 . 140 
.057 
.040 
.035 
.017 
.484 
.020 


793 


Minus  value  of  pomace,  1029  lbs.  at  Sy^c  lb. 
(468  kilograms  at  .5  pstas) 

Net  cost 


25.74 
140.90  pstas. 
per  quintal 


.123 

$.670  per 
gallon 


*  "El  Aceite  de  Oliva;  Besumen  hecho  por  la  Junta  Consultiva  Agronomica 
de  Madrid.  1923."  Printed  by  and  obtained  from  Los  Hijos  de  M.  C.  Her- 
nandez, Libertad  16,  Madrid,  Spain.  This  report  gives  a  great  deal  of  other 
valuable  information. 


8 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


Net  costs  in  other  provinces  were  given  as  shown  in  the  following 
table : 

TABLE  5 

Relation  Costs  of  Production  of  Oil  in  Several  Spanish  Provinces,  1922 
(Includes  cost  of  fruit  and  manufacture) 


Province 

Net  cost  per  quintal 
in  pesetas 

Net  cost  per  gallon 
in  dollars 

1.  Huelva 

140.9 
183.5 
156.4 
131.5 
172.2 
188.7 
133.8 
121.2 

$.670 

2.  Jaen 

.881 

3.  Granada 

.751 

4.  Murcia 

.635 

5.  Zaragossa 

.826 

6.  Albacete 

.906 

7.  Madrid 

.644 

8.  Cordova 

.585 

Average 

153.5 

$.736 

(b)  France. — No  data  were  obtained  on  manufacturing  costs  in 
Prance.  The  fruit  for  oil,  according  to  J.  Bonnet,  Director  of  the 
French  Olive  Service,  sold  during  the  1923  season  for  1  franc  per 
kilogram,  approximately  $43.00  per  ton. 

(c)  Italy. — The  charge  for  making  oil  for  the  grower  in  several 
factories  visited  near  Florence  was  6  per  cent  of  the  oil  produced. 
With  a  factory  value  of  75c  per  gallon  this  corresponds  to  a  cost  of 
4%c  per  gallon  for  crushing  and  pressing.  However,  in  this  case  the 
olives  were  furnished  by  tenants  and  the  oil  mill  was  owned  by  the 
landlord,  who  took  as  rent  half  the  oil.  Wages  were  low  in  this  fac- 
tory, 10  lira  a  day,  approximately  45c  a  day  for  men.  Women  were 
paid  3-4  lira,  about  lSy2c  to  18c  a  day,  for  picking  olives. 


CULTURE 

The  culture  of  olives  for  oil  making  is  similar  to  that  of  olives  for 
pickling,  as  described  in  Circular  278,  "Olive  Pickling  in  Mediter- 
ranean Countries."  Therefore,  this  information  will  not  be  repeated 
here.  In  oil  olive  orchards,  however,  the  trees  are  generally  not  so 
well  cared  for  as  in  orchards  producing  pickling  olives  and  inter- 
cropping is  more  prevalent. 

In  the  culture  of  olive  trees  in  Italy,  intercropping  is  very  common. 
Since  this  phase  of  olive  culture  was  not  discussed  in  the  report  noted 
above,  a  brief  description  of  this  practice  in  Italy  will  be  presented. 


Circular  279]  OLIVE  OIL   IN   SOUTHERN   EUROPE  9 

According  to  Dore,  in  1922  of  the  total  olive  area  in  Italy,  4,226,000 
acres  produced  other  crops  in  addition  to  olives  and  1,433,000  acres 
(about  one-third  of  the  total  area)  produced  olives  only.  This  con- 
dition explains  Italy's  relatively  low  yield  of  olives  per  acre.  The 
trees  are  usually  planted  farther  apart  in  orchards  where  intercrop- 
ping is  practiced.  Hay,  grain,  and  grapes  are  the  most  common  inter- 
crops, although  near  the  large  cities  vegetables  are  often  grown 
between  the  rows.  The  farmers  admit  that  dual  cropping  is  not 
beneficial  to  the  trees,  but  say  that  they  must  intercrop  in  order  to 
obtain  other  necessary  foods. 

The  olive  fly  is  a  very  serious  pest  in  some  of  the  oil  producing 
regions  of  southern  Europe,  notably  in  the  Tortosa-Reus  district  of 
northern  Spain,  the  Tuscany  region  of  central  Italy,  and  the  Nice 
district  of  France.  The  fly  larvae,  where  infestation  is  severe,  render 
the  fruit  soft  and  "worm-eaten,"  thus  permitting  rancidification  of 
the  oil  in  the  fruit.  Oil  from  such  fruit  is  high  in  free  fatty  acid  and 
of  very  poor  flavor.  As  noted  in  the  publication  on  olive  pickling 
in  southern  Europe  (Circular  278),  the  governments  of  southern 
European  countries  are  expending  a  great  deal  of  money  and  effort 
to  devise  and  apply  control  measures.  At  present  the  Berlese  method 
of  spraying  the  trees  frequently  with  a  sweetened  arsenical  spray  is 
the  most  promising,  but  has  not  given  very  satisfactory  control. 

OIL  VARIETIES  OF  OLIVES 

The  pickling  varieties  of  olives,  such  as  the  Sevillano,  Ascolano, 
Lucques,  and  Santa  Catarina,  are  considered  inferior  to  certain  other 
varieties  that  are  more  generally  used  for  oil  making.  Nevertheless, 
limited  quantities  of  cull  pickling  olives  are  used  for  oil. 

(a)  Spain. — In  Andalusia  (southern  Spain)  the  Zorzaleiia  is  the 
most  important  oil  variety.  The  fruit  is  of  larger  average  size  than 
most  oil  olives,  crops  are  large  and  regular  and  the  quality  of  the  oil 
is  good.  The  trees  produce  denser  foliage  than  Sevillano  trees  and 
more  bearing  wood  is  left  in  pruning  than  upon  Sevillano  and  Man- 
zanillo  trees  grown  in  the  same  orchards.  The  fruit  resembles  the 
Mission  olive  somewhat  in  appearance,  although  smaller.  In  addition 
to  its  value  for  oil  making  the  Zorzalena  is  of  fair  pickling  quality, 
and  is  used  extensively  for  the  preparation  of  salt  cured  olives,  for 
domestic  consumption.  According  to  the  former  American  Consul 
of  Seville,  W.  T.  Gracey,  the  Zorzalena  and  Nevadillo  Negro  may  be 
the  same  variety;  the  name  varying  according  to  the  locality  where 
grown. 


10  UNIVERSITY    OF    CALIFORNIA — EXPERIMENT   STATION 

The  Lechin  ("milk  olive")  is  also  an  important  variety — one  that 
is  very  rich  in  oil.    The  tree  is  resistant  to  frost. 

The  Nevadillo  Blanco  is  an  early  variety  grown  extensively  in  the 
provinces  of  Cordoba,  Jaen  and  Cadiz — important  oil  producing 
provinces.  The  crops  are  large  and  the  fruit  exceptionally  rich  in  oil. 
The  Nevadillo  Negro  yields  excellent  oil  and  is  said  to  give  a  larger 
yield  of  oil  from  a  given  weight  of  fruit  than  any  other  variety  in 
Jaen  province.  This  is  said  by  some  to  be  the  same  as  the  Zorzalena, 
In  the  province  of  Seville  the  plantings  consist  of  the  following 
varieties : 

Zorzalena*  70  per  cent 

Lechin 12  per  cent 

Gordal  (Sevillano) 10  per  cent 

Manzanillo  7  per  cent 

Other  varieties  1  per  cent 

In  the  Tarragona  district  (Tortosa,  Tarragona,  Barcelona,  Reus) 
varieties  other  than  those  listed  above  are  grown.  The  Arbequina, 
Morruda,  Sevillenca,  Grossal,  and  Farga  are  probably  the  most  im- 
portant. Many  other  varieties  are  grown,  among  them  the  Verdal, 
Verdarola,  Curibella,  Palomar,  Beearnda,  and  Vera,  Some  of  these 
varieties  are  grown  in  other  districts  under  other  names,  it  being 
characteristic  of  Spanish  growers  to  vary  the  name  of  the  variety 
according  to  the  locality.  Thus,  according  to  W.  T.  Gracey,  former 
American  Consul  of  Seville,  the  Zorzalena  of  Andalusia  is  known  as 
Hoji  blanca  in  Alicante  and  Cadiz;  the  Negrito  y  Lucio  in  Granada; 
the  Moradillo  in  Almeria  ;  Gordal  in  Avila;  Zorzalena  and  Cordobes 
in  Badajoz ;  Nevadillo  in  Cuidad  Real :  and  so  on  for  other  provinces. 
Similarly  Italian  and  French  varieties  are  grown  and  known  by 
various  names  according  to  the  locality. 

Literally  hundreds  of  varieties  are  grown  for  oil  and  the  nomen- 
clature is  correspondingly  extensive  and  involved. 

See  figure  3  for  appearance  of  important  Spanish  oil  olives. 

(b)  France. — In  the  olive  oil  factories  visited  in  Aix-en-Provence 
and  Nimes  the  principal  varieties  observed  were  those  used  for 
pickling,  e.g.,  the  Picholine,  Lucques,  and  Verdal.  These  are 
described  briefly  in  Circular  278.  Other  important  varieties  listed  by 
de  Mazieresf  ere  Rouget,  Pigale,  Calletier,  Pendoulier,  Oliviere,  and 
Salonenque. 

*  These  figures  are  given  in  a  report  by  the  Spanish  Government,  1923,  and 
entitled  "El  Aceite  de  diva."     (See  page  43.) 

t  de  Mazieres,  A.  E.  La  Culture  de  1 'Olivier.  J.  B.  Bailliere  et  Fils,  Paris, 
publishers. 


Circular  279] 


OLIVE    OIL    IN    SOUTHERN    EUROPE 


11 


(c)  Italy. — There  are  a  great  many  varieties  of  olives  grown  for 
oil  in  Italy;  no  less  than  three  hundred  varieties  according  to  Aloi.* 
The  College  of  Agriculture  at  Florence  has  recommended  the  follow- 
ing varieties  for  planting  for  oil  making  in  central  Italy :  the  Cor- 
regiolo  or  Frantoio,  the  Leccino  (said  to  be  the  same  variety  as  the 
Lechin  of  Spain),  and  the  Morinello.  Other  important  varieties  grown 
in  Italy  are  the  Corniola,  Taggiasea,  Pignola,  Colombaia,  Ogliaia, 
Caltabellotese,  Agostino,  Biancolilla,  Casertana,  and  Rasciola. 


Fig.  3. — Oil  olives  of  northeastern  Spain. 
No.  1,  Arbequina;  No.  2,  Farga;  No.  3,  Morruda;  No.  4,  Sevillenca. 


(d)  Suitability  for  California. — It  is  doubtful  whether  it  would  be 
advisable  to  import  European  oil  olive  varieties  for  growing  in  Cali- 
fornia, because  our  industry  is  based  upon  the  production  of  pickled 
olives.  However,  the  oil  made  from  our  Mission  olives  is  considered 
excellent.  The  oil  olives  are  in  general  small  and  therefore  unsuitable 
for  commercial  pickling.  While  the  quality  of  our  oil  would  be 
improved  by  growing  these  varieties,  it  would  probably  be  impossible 

*Ant.  Aloi,  l'Olivo  e  Olio  (Milan). 


12 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


for  Caliiornian  growers  and  oil  makers  to  compete  with  the  Europeans 
in  price. 

However,  it  is  believed  that  one  or  more  of  the  dual  purpose 
varieties  suitable  both  for  oil  making  and  pickling,  such  as  the  French 
Verdal  and  Picholine,  the  Italian  Agostino  or  the  Spanish  Rapasayo, 
might  find  a  place  in  California  olive  culture  similar  to  that  now  held 
by  the  Manzanillo  and  Mission. 


Fig.  4. — Harvesting  olives  for 
oil,  Spain. 


Fig.  5. — Ladder  used  in  north- 
ern Spain  for  harvesting  olives. 
Central  leg  is  on  a  pivot. 


HARVESTING,  TRANSPORTING  AND  STORING  THE   OLIVES 

Harvesting,  transporting,  and  storing  olives  for  oil  making  are  now 
given  much  more  consideration  than  formerly,  because  the  refiners  who 
buy  much  of  the  oil  from  the  mills  and  the  government  olive  oil  experts 
have  impressed  upon  the  grower  and  mill  operator  the  effect  of  these 
important  preliminary  steps  on  quality  and  price. 

(a)  Harvesting. — The  harvesting  of  olives  for  oil  begins  early  in 
November  in  southern  Spain,  while  in  northern  Spain,  southern 
France,  and  central  Italy  the  season  is  about  one  month  later  and 
extends  to  about  February  1  or  later.  Olives  were  being  crushed  on 
February  28  in  a  factory  visited  near  Florence,  Italy. 

All  mill  operators  interviewed  stated  that  they  wished  the  fruit 
to  be  black  in  color  when  harvested  for  oil.  J.  Bonnet,  Director  of 
the  French  Olive  Service,  has  found  that  the  oil  is  of  best  quality 


Circular  279] 


OLIVE    OIL    IN    SOUTHERN    EUROPE 


13 


when  made  from  fruit  in  which  the  flesh  has  become  purple.  Before 
this  stage  he  finds  the  oil  acrid  and  of  poor  flavor ;  beyond  this  stage 
the  oil  is  apt  to  be  flat  in  flavor  and  light  in  color.  Very  little  of  the 
fruit  observed  in  Spanish,  French,  and  Italian  factories  conform  to 
Mr.  Bonnet's  ideal-— much  of  it  was  overripe,  shriveled,  or  frosted. 

Harvesting  as  observed  in  these  countries  is  conducted  in  one  of 
three  ways :  The  .first  of  these  consists  in  picking  from  the  ground 
fruit  which  has  fallen  naturally  or  which  has  been  knocked  from  the 
tree  by  light  poles  or  rakes.    Insects,  particularly  the  olive  fly,  cause 


Fig.  6. — Shipping  oil  olives  in  bags,  Spain. 


considerable  fruit  to  fall  prematurely,  and  the  first  picking  usually 
consists  of  such  fruit.  It  makes  an  inferior  oil.  While  government 
oil  experts  and  others  condemn  the  method  of  harvesting  by  knocking 
the  fruit  from  the  trees  because  of  injury  to  both  fruit  and  bearing 
wood,  it  is  nevertheless  a  very  common  practice.     (See  figure  4.) 

Knocking  the  fruit  on  to  burlap  or  canvas  sheets  is  a  method  of 
harvesting  practiced  in  a  number  of  orchards.  A  great  many  leaves 
and  small  twigs  fall  with  the  olives  and  must  be  removed  by  hand  or 
by  a  fanning  mill.  Leaves  are  objectionable  because  of  the  green 
coloring  matter  (chlorophyll)  and  acrid  compounds  dissolved  from 
them  by  the  oil. 

The  third  method,  hand  picking  from  the  tree,  is  of  course  the 
best,  but  not  so  generally  used  as  might  be  expected. 

Baskets  or  sacks  suspended  from  the  neck  are  generally  used  in 
preference  to  metal  buckets  for  holding  the  fruit  during  picking. 
Three-legged  ladders  such  as  that  shown  in  figure  5  were  seen  in  many 
orchards.    Large  two  handled  baskets  and  sacks  are  used  for  holding 


14 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


the  fruit  after  picking:  baskets  are  preferable  but  more  costly  and 
difficult  to  handle. 

(b)  Transportation. — To  most  of  the  factories  visited  the  fruit 
was  delivered  in  burlap  bags.  These  containers,  while  cheap  and  con- 
venient, are  conducive  to  bruising  and  are  therefore  condemned  by 
olive  oil  authorities.  In  southern  Spain  the  olives  are  generally  hauled 
in  bulk  in  large  ox-carts  lined  with  grass  matting— each  cart  holding 
about  a  ton  of  fruit — or  in  angorillas  (side  bags)  on  donkey-back.  Bags 
are  used  for  transportation  by  rail.  (See  figure  6;  also  illustrations 
in  Circular  278.) 


Fig. 


-Storage  bins  for  fresh  olives  in  oil  factory  near  Seville. 


(c)  Storage. — At  one  time,  storage  of  the  olives  in  deep  bins  to 
undergo  fermentation  and  softening  before  crushing  was  an  almost 
universal  practice  in  Spain,  according  to  several  oil  makers  who  were 
questioned  on  this  point.  At  present  the  trend  is  away  from  this 
practice  and  toward  the  use  of  fruit  direct  from  the  orchard  before  it 
has  had  time  or  opportunity  to  mold  or  ferment. 

Nevertheless,  deep  bins  are  still  common  in  the  less  modern  factories 
and  are  still  in  use  in  many  of  them.  A  typical  bin  observed  in  a 
small  factory  is  shown  in  figure  7.  The  fruit  undergoes  fermentation 
in  the  lower  depths  of  the  bin  and  molding  near  the  surface — a  small 


Circular  279] 


OLIVE    OIL    IN    SOUTHERN    EUROPE 


15 


stream  of  "black  liquor"  of  rancid  odor  trickles  from  the  outlet,  and 
the  general  condition  of  the  fermenting  and  rotting  mixture  is  bad. 
Oil  from  fruit  handled  in  this  way  has  been  shown  to  be  high  in  free 
fatty  acid;  it  is  of  poor  flavor  and  often  of  very  "rancid"  odor. 
However,  the  binning  treatment  facilitates  pressing  and  makes  possible 
the  pressing  of  a  relatively  large  amount  of  fruit  with  a  small  amount 
of  equipment  by  prolonging  the  season.  Oil  from  such  factories  is 
generally  cheap  and  finds  a  local  undiscriminating  market.  In  fact, 
some  "hardened"  consumers  state  that  they  prefer  such  oil  because 
of  its  ' '  distinctive ' '  flavor. 


i 


ft*. 


^     ^ 


Fig.  8. — Mill  and  oil  storage  jar  of  the  ancient  Romans. 
Pompeii,  Italy. 


Storage  of  the  fruit  in  sacks  is  little  better  than  in  deep  bins. 
Much  fermented  and  moldy  fruit  was  observed  in  such  containers. 

Storage  in  shallow  bins  on  the  floor  level,  with  occasional  shoveling 
over  of  the  fruit,  was  in  use  in  many  factories  with  apparently  good 
results.  Such  bins  are  convenient  in  cooperative  plants  where  each 
member's  fruit  must  be  kept  separate  and  where  several  days'  delivery 
from  one  grower  is  necessary  to  give  enough  fruit  for  a  run  in  the  mill. 

Bonnet  (Director  of  the  French  Olive  Service)  and  others  stated 
that  storage  in  brine  (5-6  per  cent  salt,  20-25°  salometer)  is  the  best 


16 


UNIVERSITY    OF    CALIFORNIA — EXPERIMENT   STATION 


method  for  long  storage  periods,  and  that  if  properly  applied  does  not 
injure  the  quality  of  the  oil.  This  agrees  with  California  experience. 
All  who  were  questioned,  however,  agreed  that  the  ideal  method  is 
to  crush  and  press  on  the  day  of  picking.  One  factory  in  Spain,  the 
Union  Oliverera  of  Carmona  (makers  of  oil  for  H.  J.  Heinz  Co.) 
make  a  feature  of  this  practice.  No  fruit  is  stored.  The  delivery  of 
each  day  is  crushed  and  pressed  on  the  day  or  night  of  delivery.  This 
practice  has  made  it  necessary  to  install  considerably  more  equipment 
than  would  otherwise  be  required,  but  it  is  believed  that  the  high 
quality  of  the  oil  and  the  correspondingly  high  price  more  than  offset 
the  extra  cost. 


Fig.  9. — Mule  drawn  mill  in  farmer's  olive  oil  factory,  near  Seville. 


EXTE ACTION  OF  THE  OIL 

Crushing  and  pressing  machinery  varies  greatly  in  design  and 
efficiency,  and  mills  and  presses  similar  to  those  used  by  the  ancient 
Romans  are  to  be  found  near  mills  with  the  most  modern  equipment. 
Figure  8  illustrates  an  ancient  oil  mill  and  oil  storage  jar  at  Pompeii. 

1.  Crushing.. — In  small  mills  in  Andalusia,  Spain  (Seville,  Cordova, 
Jaen,  and  at  other  places)  will  be  found  the  so-called  Andalusian 
single  roll,  truncated  cone  edge  runner  (mule  or  ox  drawn),  such  as 
is  shown  in  figure  9.  The  fruit  is  fed  in  slowly  from  a  small  hopper 
above  the  edge  runner.  As  the  latter  revolves  in  the  stone  or  concrete 
basin,  the  olives  are  crushed  and  forced  outward  to  the  circular  trough 
shown  in  the  figure.  If  insufficiently  crushed  the  fruit  is  shoveled 
beneath  the  edge  runner  to  be  crushed  a  second  time.     The  pomace, 


Circular  279] 


OLIVE    OIL    IN    SOUTHERN    EUROPE 


17 


after  the  first  pressing,  is  also  often  ground  beneath  this  edge  runner 
before  the  second  and  third  pressing. 

In  the  Tarragona  district  a  single,  very  heavy  edge  runner  of  the 
form  shown  in  figure  10  is  used  in  the  small  mills.  One  crushing  is 
sufficient,  because  the  fruit  is  fed  in  front  of  the  wheel  only  as  rapidly 
as  it  can  be  ground  thoroughly.  Electricity  is  the  usual  power, 
although  animal  power  is  also  common. 


Fig.  10. — Single  wheel  edge  runner,  Tortosa,  Spain. 
Common  in  mills  in  northeastern  Spain. 


In  the  modern  mills  in  Andulusia,  rolls  of  the  appearance  shown 
in  figures  11  and  12  are  used.  Three  truncated  cones  of  granite 
revolve  in  a  steel  or  stone  bowl.  In  addition  the  two-wheel  Italian 
style  of  edge  runner  is  used  to  complete  the  grinding  started  in  the 
three-roll  mill  or  to  regrind  the  pomace.  (See  figures  11  and  12.) 
According  to  the  report  of  the  Spanish  Government  previously  re- 
ferred to  (see  page  43),  the  capacities  of  the  different  types  of  Spanish 
mills  are  for  a  one-roll  mill  -10  quintals  (8800  lbs.)  in  24  hours;  two- 
roll  mill,  60  quintals  (13,200  lbs.),  and  three-roll  mill,  80  quintals 
(17,600  lbs.)  in  24  hours. 

In  the  larger  factories  the  olives,  before  going  to  the  edge  runner, 
usually  are  ground  in  a  "trituradora,"  a  machine  consisting  essenti- 
ally of  two  horizontal  and  parallel  screws,  revolving  toward  each 
other.  The  treatment,  it  is  claimed,  increases  the  capacity  of  the 
edge  runner  and  the  yield  of  oil.     As  in  California,  fruit  in  some 


18 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


factories  goes  direct  to  the  press  from  the  "trituradora"  or  its 
equivalent.  In  France,  the  olives  are  usually  given  a  preliminary 
crushing  between  fluted,  steel  rolls.  These  rolls  accomplish  about  the 
same  effect  as  the  Spanish  "trituradora"  mentioned  above.  The 
olives  are  then  ground  in  an  edge  runner  consisting  of  two  heavy, 
granite  "bull  wheels"  revolving  in  a  steel  bowl.      The  French  edge 


Fig.  11. — Andalusian  edge  runner  with  three  rolls. 
In  a  modern  factory,  Carmona,  Spain. 

runner  is  very  similar  in  appearance  to  that  in  use  in  Calif ornian 
olive  oil  factories.  According  to  Chappelle  and  Ruby*  the  Labin  and 
Druge  crusher,  consisting  of  eight  fluted  cylindrical  rolls  in  super- 
imposed pairs,  crushes  the  olives  sufficiently  to  permit  pressing  with- 
out treatment  in  an  edge  runner.  It  may  be  used  also  to  replace  the 
edge  runner  in  grinding  the  pomace  after  the  first  pressing. 


*  Chapelle,  J.  and  Ruby,  J.  L  'Huilerie  Moderne.  Published  by  Librairie 
Polytechnique.  Ch.  Beranger,  Editeur,  15  Rue  des  Saints-Peres,  Paris.  (Out  of 
print.) 


Circular  279]  OLIVE   OIL   IN   SOUTHERN   EUROPE 


19 


n 


Fig.  12. — View  of  an  oil  factory  near  Seville. 
At  left,  pomace  breaker.     At  right,  three  roll  edge  runner, 


Fig.  13. — Two  types  of  Italian  olive  edge  runners,  near  Florence. 
Both  driven  by  water  power. 


20 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT   STATION 


The  crushing  methods  observed  in  small  Italian  factories  were 
similar  to  those  previously  described  for  northern  Spain.  The  mills 
are  shown  in  figure  13.  The  crusher  in  most  factories  visited  con- 
sisted of  a  single  granite  "bull  wheel"  or  edge  runner,  revolving  in 
a  stone  bowl,  and  was  operated  by  animal  power  or  water  power.  In 
the  larger  mills  the  crushing  equipment  is  similar  to  that  used  in 
France,  the  edge  runners  being  of  the  two-wheel  type  and  power 
driven. 


Fig.  14. — Hand-power  press  in  small  Italian  factory  near  Florence. 


2.  Presses. — The  simplest  press  seen  in  use  was  the  hand  operated 
wooden  screw  press  of  Italy,  shown  in  figure  14.  The  lever  of  the 
press  shown  in  the  illustration  was  turned  by  four  men  who  received 
45c  a  day  each. 

The  beam  press  of  the  Romans  is  used  in  many  small  mills  in  Spain. 
The  press  consists  of  a  large  square  wooden  bean  about  35-40  feet 
long,  pivoted  at  one  end  and  fitted  with  a  long,  vertical,  wooden  screw 
at  the  opposite  end.  Beneath  the  press  near  the  pivot  end  is  situated 
the  floor  of  the  press,  on  which  rest  the  cloths  filled  with  crushed  olives. 


Circular  279] 


OLIVE    OIL    IN    SOUTHERN    EUROPE 


21 


(See  figure  15.)  Both  of  these  presses  are  inefficient  and  give  low 
yields  of  oil,  although  they  are  simple  and  inexpensive. 

Various  styles  of  metal,  hand  power  screw  presses  are  also  used 
in  many  small  factories. 

Hydraulic  presses  are  almost  universally  used  in  the  large  fac- 
tories. These  are  similar  to  those  used  in  Californian  factories, 
although  some  of  the  French  hydraulic  presses  give  considerably 
higher  pressure  than  is  normally  obtained  in  either  Spain  or  Cali- 
fornia,   See  figures  16,  17,  and  18  for  appearance  of  typical  presses. 


Fig.  15. — Beam  press  used  in  small  factories  of  southern  Europe. 
(After  Chapelle  and  Ruby.) 


3.  Pressing  and  Regrinding. — Press  "cloths"  are  usually  made  of 
woven  esparto  grass  or  coconut  fiber.  (See  figure  19.)  Camel's  hair  is 
used  in  some  factories  for  the  second  and  third  pressings  if  very  heavy 
pressure  is  to  be  applied.  The  press  cloths  are  usually  circular  and 
about  27-30  inches  in  diameter.  For  hydraulic  presses  they  are  often 
made  with  a  hole  in  the  center  through  which  the  central  steel  post 
of  the  press  is  passed.  The  edges  of  each  cloth  ("capacho"  in  Spanish, 
"scourtin"  in  French)  are  turned  inward  for  about  three  inches 
(see  figure  19)  so  that  when  one  is  placed  above  another  a  tight  seal 
is  made  around  the  edges. 

The  ground  olives  from  the  edge  runner  are  shoveled  or  scooped 
with  the  hands  into  the  press  cloth  in  place  in  the  press  or  on  a 
portable  press  floor,  and  the  ground  mass  is  then  spread  into  place  with 


22 


UNIVERSITY    OF    CALIFORNIA- — EXPERIMENT   STATION 


the  hands.    The  filled  cloths  are  built  up  one  above  the  other  to  give 
the  "cheese"  as  shown  in  figures  14,  17,  and  18. 

The  first  pressing  (in  whatever  manner  applied)  removes  most  of 
the  easily  expressable  juice,  together  with  some  oil,  This  first  oil, 
"virgin"  oil,  is  considered  the  best  and  is  kept  separate  from  the 
second  and  third  pressings. 


Pig.  16. — Hydraulic  olive  press  in  action,  Tortosa,  Spain. 

The  pomace  is  in  Spain  and  Italy  reground  before  the  second 
pressing.  The  Spanish  pomace  grinder  consists  of  a  cylinder  fitted 
with  spikes  and  which  revolves  toward  a  plate  also  fitted  with  spikes. 
This  machine  is  known  as  a  "remoledora."  In  many  factories,  par- 
ticularly small  ones,  the  pomace  is  ground  in  an  edge  runner.  In 
such  cases,  a  small  amount  of  water  is  often  added  to  the  pomace  from 
the  first  pressing.  Water  is  always  added  before  the  third  pressing. 
The  addition  of  water  before  the  second  pressing  is  condemned  by  all 
European  olive  oil  authorities  interviewed ;  but  if  water  is  to  be  added, 
these  experts  agree  that  cold  water  is  preferable  to  warm,  because  it 
dissolves  less  of  the  objectionable  compounds  from  the  pulp. 


Circular  279" 


OLIVE    OIL    IN    SOUTHERN    EUROPE 


23 


In  France  two  pressings  only  are  used  in  the  modern  factories 
visited,  and  the  pomace  is  not  ground  between  pressings.  A  moderate 
pressure  is  first  applied  to  remove  most  of  the  juice.  The  cloths  are 
then  transferred  to  the  second  press  without  disturbing  the  press 
cakes,  and  very  heavy  pressure  applied.  The  yield,  according  to  J. 
Bonnet,  is  excellent,  the  final  pomace  containing  only  8  per  cent  of 
oil  or  less.  The  secret  of  success  in  this  method  lies  in  the  use  of  a 
very  powerful  press  for  the  second  pressing.  (See  figure  18.)  Labor 
costs  are  materially  cut  and  the  capacity  of  the  presses  considerably 
increased  by  this  method. 


Fig.  17. — Upper,  Hydraulic  pumps  with  variable  speed  drive.    Lower,  line-up 
of  presses  and  crushers.    Both  views  in  a  modern  factory,  Spain. 


In  Spain  three  pressings  are  given.  In  the  small  factories  in 
central  Italy,  three  pressings  arc  also  applied,  and  then  the  pomace 
from  the  third  pressing  is  ground  in  water  in  an  edge  runner,  as 
shown  in  figure  20,  until  the  pulp  is  thoroughly  disintegrated.  This 
water,  with  suspended  pulp,  flows  to  several  settling  tanks,  shown  in 
figure  20,  and  eventually  to  a  stream.  Oil  rises  in  the  various  tanks 
and  is  recovered  by  skimming  or  overflow.  The  ground  seeds  and 
settlings  are  removed  from  the  bottom  of  the  first  tank  periodically. 
Figure  20  illustrates  this  system  of  pomace  treatment.  The  oil  is  of 
very  poor  quality,  but  often  suitable  for  refining.  If  too  rancid  for 
refining,  it  is  always  salable  for  soap  stock.    Chappelle  and  Ruby  (see 


24 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


previous  reference,  page  43)  state  that  2  to  5  per  cent  of  oil  is  recover- 
able by  this  method.  Much  higher  yields  can  be  obtained  by  treating 
the  pomace  with  an  oil  solvent  (see  page  37). 

4.  Separating  Oil  and  Juice. — In  all  of  the  Spanish  and  Italian 
oil  factories  visited,  the  mixed  juice  and  oil  from  the  press  are  allowed 
to  settle  and  are  then  separated  by  decantation  or  by  skimming.  In 
the  modern  Spanish  factories  glazed  tile  line  tanks  receive  the  liquid 


JLfdiizer 


Fig.  18. — High  pressure  hydraulic  press  used  in  Frr 
(After  Ohapelle  and  Euby.) 


*e  for  second  pressing. 


from  the  press.  Two  or  more  of  these  tanks  are  connected  in  series 
by  syphons  extending  nearly  to  the  bottom  of  each  tank.  The  oil  rises 
to  the  surface  and  is  removed  through  an  opening  near  the  top  of  the 
tank.    This  separator  may  be  operated  continuously.     (See  figure  21.) 

In  small  factories  that  were  visited  the  mixed  liquids  were  placed 
in  tanks  and  after  settling  the  oil  was  separated  by  skimming  by  hand. 

Tin-lined,  sheet  metal  tanks  fitted  as  shown  in  figure  22  were 
observed  in  Spain.  Similar  tanks  have  been  used  in  some  California 
factories.    Separation  may  be  made  either  intermittent  or  continuous 


Circular  279]  OLIVE   OIL   IN   SOUTHERN   EUROPE 


25 


Fig.  19. — Esparto  grass  press  bag  ("Capacho  "),  Spain. 


^rox  ***** 


Fig.  20. — Equipment  used  in  Italy  for  recovery  of  oil  from  pomace  by  grind- 
ing in  water  and  flotation.  (After  Chapelle  and  Ruby.)  A,  edge  runner.  B, 
Stirrer.  C,  Tanks  for  separation  of  oil  and  water,  a,  Connecting  conduit. 
c,  Water  inlet,     h,  Stirrer.     I,  Waste  skins  and  pulp. 


26  UNIVERSITY    OF    CALIFORNIA EXPERIMENT   STATION 

In  France  separation  of  the  oil  and  juice  by  centrifugal  force  is 
rapidly  displacing  other  methods.  The  machine  is  similar  in  appear- 
ance to  a  milk  separator  and  operates  on  the  same  principle.  The 
liquid  from  the  press  is  elevated  to  a  small  tin-lined  tank,  into  which 
it  flows  through  a  fine  screen  which  removes  particles  of  pulp,  skin, 
etc.  Unless  removed,  this  solid  matter  quickly  clogs  the  bowl  of  the 
separator.  The  bowl  of  the  machine  in  most  common  use  (the  Turbina 
Hignette)  revolves  at  from  6000  to  10,000  r.p.m.,  according  to  its 
diameter.  Separation  is  instantaneous,  continuous,  and  complete. 
Settling,  decantation,  and  skimming  are  dispensed  with.  The  oil 
makers  who  were  interviewed  expressed  full  approval  of  the  machine 
and  the  process.  Centrifugal  separation  is  in  use  in  at  least  one 
California  factory  and  it  is  possible  that  others  could  use  it  with 
advantage. 

5.  Other  Methods  of  Extracting  Oil. — In  addition  to  the  standard 
methods  described  above,  several  methods  are  in  use  in  southern 
Europe  or  have  been  used  experimentally. 

(a)  Continuous  press. — One  of  the  most  promising  of  these  is  the 
Colin  method  in  which  a  continuous  press  is  used.  This  consists  of 
two  screws  revolving  in  a  perforated,  horizontal  cylinder,  with  an 
outlet  into  which  fits  an  adjustable  metal  cone.  The  size  of  the  outlet 
and  thereby  the  pressure,  can  be  adjusted  by  adjusting  the  position 
of  the  cone.  In  experiments  this  machine  has  given  pomace  contain- 
ing only  7  per  cent  of  oil,  indicating  unusually  high  extraction.  The 
difficulty  has  been  to  separate  the  emulsified  oil  and  juice — the 
machine  grinds  the  pulp  very  fine,  making  a  mixture  of  pulp,  oil,  and 
juice  that  settles  with  great  difficulty.  Chappelle  and  Ruby  (see 
reference,  page  43)  believe  that  this  difficulty  can  be  overcome.  A 
continuous,  mechanical  process  that  wiir eliminate  hand  labor  is  highly 
desirable  for  use  in  California.  Such  a  press  has  recently  been 
designed  and  built  by  the  California  Press  Manufacturing  Company, 
and  is  said  to  have  given  good  results  in  commercial  size  experiments. 

(b)  Acapulco  process. — Professor  Don  Guillermo  Quintanillo  has 
experimented  with  this  process  and  when  interviewed  at  the  National 
School  of  Agriculture  in  Madrid  reported  that  it  is  now  in  successful 
operation  in  a  factory  in  southern  Spain.  Other  Spanish,  French,  and 
Italian  olive  oil  experts  who  were  consulted  did  not  consider  the 
process  very  practical.  It  has  been  greatly  simplified  by  Quintanillo 
and  others,  and  may  eventually  come  into  general  use. 

The  process  as  originally  conducted  consisted  in  pitting  the  olives ; 
grinding  the  pulp  to  a  fine  paste;  placing  this  paste  in  a  horizontal 


Circular  279] 


OLIVE    OIL    IN    SOUTHERN    EUROPE 


27 


cylinder  under  a  high  vacuum,  where  it  was  rubbed  against  a  very 
fine  cylindrical  screen,  which  permitted  the  oil  to  pass  but  which 
retained  the  pulp  and  juice.  The  vacuum  has  been  found  unnecessary 
and  is  no  longer  used.  The  pitting  machine  and  grinder  have  been 
replaced  by  a  single  machine  which  removes  the  pits  and  converts  the 
olive  flesh  into  a  fine  pulp.  It  was  understood  from  Professor 
Quintanillo  that  this  machine  is  similar  to  a  tomato  pulper.  It  has  a 
capacity  of  about  30  tons  a  day. 


Fig.  21. — Glazed  tile  tanks  for  separation  of  oil  and  juice 
in  a  modern  mill,  Spain. 


The  oil  separating  machine  consists  of  a.  metal  cylinder,  the  lower 
half  of  which  is  a  hemicylindrical  sheet  of  nickel  with  very  fine 
perforations.  Brushes  attached  to  a  central  shaft  revolve  slowly, 
8-10  r.p.m.,  and  bring  about  the  separation  previously  mentioned. 
Professor  Quintanillo  states  that  the  separation  is  accomplished 
essentially  by  filtration  "in  motion"  and  that  it  depends  very  largely 
upon  the  difference  in  surface  tension  of  olive  oil  and  water.  Accord- 
ing to  Quintanillo,  the  experimental  plant  has  a  capacity  of  18,000 
kilograms,  nearly  20  tons,  in  24  hours. 


28  UNIVERSITY   OF    CALIFORNIA — EXPERIMENT   STATION 

He  claims  for  it  the  following  advantages : 

1.  Greater  yield  of  oil  than  by  pressing. 

2.  Better  quality  of  oil — all  being  of  virgin  oil  quality.  There  is 
but  one  grade. 

3.  Lower  acidity. 

4.  Greater  economy  of  operation  and  far  greater  capacity  per  unit 
of  power  expended. 

5.  Less  skill  and  experience  required.  "Anyone  can  make  good 
oil  with  this  process. ' ' 

6.  Less  space  required  for  equipment. 

7.  Greater  simplicity  of  operation. 

8.  Obtaining  a  valuable  stock  food  as  a  by-product. 

A  commission  appointed  by  the  Spanish  Department  of  the  Interior 
reported  favorably  upon  the  process.  Professor  Quintanillo  informed 
the  writer  that  he  is  glad  to  give  further  information. 

(c)  Centrifugal  Separation  of  Pulp  and  Oil. — This  has  been  tested 
and  although  partial  success  was  attained,  the  method  has  not  been 
perfected,  insofar  as  J.  Bonnet,  Director  of  the  Olive  Service  of 
France,  Professor  Quintanillo  of  Madrid,  Dr.  Matons  of  the  University 
of  Barcelona,  and  others  were  aware. 

(d)  By  Diffusion. — According  to  Chappelle  and  Ruby  (see  page 
43),  oil  may  be  extracted  by  diffusion.  In  one  method  of  applying 
the  diffusion  principle  the  olives  are  ground  to  a  paste,  mixed  with  a 
salt  solution  (sea-water  will  do),  and  heated  with  agitation  for  several 
hours.  The  oil  rises  and  the  pulp  sinks.  The  yield  is  said  to  be 
greater  than  by  pressing,  but  the  heating  injures  the  quality. 

Professor  Bracci  of  Spoleto,  Italy  has  varied  this  procedure  by 
substituting  a  dilute  alkaline  solution  for  the  brine  and  subjecting 
it  to  an  electric  current.    The  mixture  is  kept  at  40°  C.  (104°  F.). 

While  the  diffusion  process  is  still  of  doubtful  value  ,it  might  prove 
worthy  of  further  investigation. 

(e)  By  Solvent. — Trichlorethylene,  "trielene, "  is  a  cheap,  non- 
inflammable  oil  solvent  and  by  its  use  it  is  possible  to  prepare  an  edible 
oil  from  suitably  dried  olives.  According  to  Dr.  Matons,  in  charge  of 
olive  oil  investigations  at  the  University  of  Barcelona,  this  method 
has  been  applied  successfully  at  an  olive  experiment  station  in  Italy. 
One  difficulty  is  economical  drying.  Another  is  complete  separation 
of  the  solvent  and  oil  by  distillation.  Treatment  under  a  high  vacuum 
with  steam  is  said  to  remove  all  trace  of  the  solvent.    Dr.  Matons  did 


Circular  279] 


OLIVE    OIL    IN    SOUTHERN    EUROPE 


29 


not  believe  the  method  very  practicable  from  a  commercial  standpoint. 
The  solvent  process  is  to  be  tested  in  Los  Angeles  during  the  present 
season,  according  to  a  letter  recently  received  from  the  owner  of  the 
solvent  equipment. 

OIL  and  WATER 


WATER 


FOAM 


fVAM 


Fig.  22.     Oil  and  juice  separator  used,  in  Spain. 
(From  "Boletin  Mensual  de  Olivicultura. ") 


NORMAL  TREATMENT  OF  THE  OIL 

The  treatment  of  the  oil  varies  somewhat  according  to  the  country, 
the  district,  and  the  manufacturer. 

1.  Washing.— Washing  the  oil  with  water,  as  practiced  in  all  fac- 
tories in  California,  is  by  noi  means  general  in  Mediterranean  oil  mills. 
In  fact,  in  the  majority  of  factories  visited  the  oil  was  not  washed 
with  water  at  all,  and  aging  and  filtration  were  relied  upon  to  remove 
the  bitterness.  In  France  washing  with  sprays  of  water  (cold  recom- 
mended in  preference  to  warm)  is  a  more  common  practice  than  in 
Spain.  Spanish  olive  oil  authorities  who  were  consulted  advised 
against  washing  of  the  oil  because  it  removes  desirable  flavors  and 
aroma. 


30  UNIVERSITY    OF    CALIFORNIA EXPERIMENT   STATION 

Washing  if  applied,  is  conducted  as  in  California,  by  sprays  of 
water.  In  one  small  factory  the  water  was  added  from  an  ordinary 
garden  sprinkling"  pot.  The  washed  oil  must  be  allowed  to  settle  and 
then  be  thoroughly  separated  from  the  sediment,  or  filtered  to  remove 
all  water — otherwise,  bacterial  growth  and  rancidification  will  ensue. 
A  temperature  above  55°  F.  and  below  70°  F.  is  recommended  during 
settling.  At  lower  temperatures  the  oil  is  viscous  and  separation  is 
imperfect;  above  70°  F.,  rancidification  is  favored.  After  the  water 
in  the  oil  has  been  completely  removed,  the  storage  temperature  is  not 
so  important, 

2.  Storage. — In  large  factories  tanks  lined  with  glazed  tile  are 
generally  used.  These  are  often  beneath  the  floor  and  of  very  large 
capacity.  In  many  small  factories,  particularly  in  Spain,  stoneware 
jars  such  as  those  shown  in  figure  23,  and  in  others  tin-lined  cylin- 
drical tanks  are  used.  See  figure  23.  The  tile-lined  (sometimes  called 
"glass-lined")  tanks  are  easily  cleaned  with  dilute  lye  solution  and 
can  be  kept  in  sound  condition.  Tin  also  is  easily  cleaned,  but  the 
pores  of  the  stoneware  jars  seen  in  several  factories  had  become 
impregnated  with  oil  which  had  become  very  rancid  and  odoriferous. 
A  good  interior  glaze  is  essential  for  such  containers. 

The  temperature  recommended  for  the  storage  room  is  above  40°  F. 
and  below  60°  F.  Below  40°  F.  the  solid  fats  are  apt  to  separate ; 
when  redissolved  in  the  oil  it  is  claimed  that  they  impart  a  "tallowy" 
taste.  Above  60°  F.,  danger  of  rancidification  increases.  However, 
very  few  of  the  factories  visited  would  be  able  to  maintain  this  tem- 
perature range.  Rather  frequent  rackings,  that  is  drawing  off  the  oil 
from  the  "foots"  (sediment)  are  made  in  most  factories  because  the 
foots  tend  to  decompose  and  cause  increase  of  acidity.  In  one  large, 
modern  factory  in  southern  Spain,  very  large,  underground,  tile- 
lined  storage  tanks  are  used  and  the  oil  frequently  racked  until  it  is 
free  from  bitterness — a  year  or  longer  being  required.  At  no  time  is 
the  oil  washed  in  this  factory. 

Storage  tanks  should  be  of  such  design  that,  when  filled,  as  small 
a  surface  of  oil  as  possible  is  exposed  to  the  air  in  order  to  reduce 
oxidation. 

3.  Filtration. — Many  different  styles  of  filters  are  in  use.  In  the 
large  refineries  plate  and  frame  filter  presses  consisting  of  metal  racks 
and  canvas  filter  cloths  are  used  because  of  their  great  capacity.  The 
oil  in  such  plants  is  mixed  with  a  "filter  aid"  such  as  infusorial 
earth  or  with  a  bleaching  material  such  as  fuller's  earth  or  decoloriz- 
ing carbon. 


Circular  279] 


OLIVE    OIL    IN    SOUTHERN    EUROPE 


31 


The  most  popular  filter  in  factories  of  large  and  moderate  size 
appeared  to  be  a  so-called  "capillary"  filter  using"  discs  of  filter  paper 
held  between  circular  metal  plates,  placed  one  above  the  other  to  form 
a  vertical  cylinder.  This  filter  produces  a  brilliantly  clear  oil,  is 
simple  in  operation,  easily  assembled  and  portable.  A  small  rotary 
pump  may  be  used  to  deliver  the  oil  to  the  filter  under  constant  pres- 


Fig.  23. — Tin-lined  tanks  and  large  earthenware  jars  used  for 
oil  storage  in  a  factory  near  Seville. 


sure,  or  the  oil  may  be  allowed  to  flow  by  gravity  from  a  supply 
tank  placed  15  to  25  feet  above  the  filter.  The  Daude  filter  of  Le 
Vigan  (Gard),  France,  is  of  the  capillary  type.    See  figure  24. 

Other  filters  used  are  made  up  of  metal  plates  between  which  are 
placed  compressed  pads  of  cotton  fiber  which  serve  as  the  filtering 
medium.     The  Vail  filter  of  Barcelona  is  of  this  type. 


32  UNIVERSITY   OF    CALIFORNIA — EXPERIMENT   STATION 

Homemade  filters  consisting  of  a  box  with  a  layer  of  cloth  covered 
cotton  can  be  found.  Porous  earthenware  vases  or  tubes  are  also  in 
use  for  small  scale  filtration.  Funnels  and  folded  filter  paper  are 
not  used  as  commonly  as  in  California. 

Any  form  of  open  filter,  such  as  a  funnel  and  paper,  exposes  a 
large  surface  of  oil  to  the  air,  for  a  relatively  long  time,  resulting  in 
loss  of  flavor,  absorption  of  odor  and  oxidation,  Such  filters  are  con- 
demned for  these  reasons  bj^  European  oil  authorities  such  as  Matons 
of  Spain  and  Bonnet  of  France.  California  oil  manufacturers  will 
do  well  to  investigate  the  French  "capillary"  filter  and  other  forms 
of  European  and  American  oil  filters  with  a  view  to  replacing  the 
present  filter  paper  and  funnel  system  of  filtration. 

4.  Demargination. — Demargination  consists  in  the  removal  of  an 
excess  of  dissolved  solid  fats.  According  to  J.  Bonnet,  Director  of 
the  Olive  Oil  Service  of  France,  and  Professor  Matons  of  Barcelona, 
European  oils  are  not  demarginated,  except  to  the  extent  that  occurs 
naturally  during  normal  storage  of  the  oil.  At  low  storage  tempera- 
tures a  considerable  amount  of  solid  fat  (stearin)  separates  and  is 
removed  by  racking.  As  stated  elsewhere,  it  is  considered  desirable 
by  some  oil  makers  to  remove  any  solid  fat  that  may  separate  during 
storage  because  of  the  development  of  a  "tallowy"  taste,  which  is 
said  to  ensue  if  the  fat  is  redissolved.  However,  in  one  large  oil 
refinery  and  cannery,  oil  which  had  partially  congealed  by  cold  during 
shipment  in  steel  drums  was  thoroughly  melted  before  canning,  thus 
redissolving  the  solid  fats.  The  flavor  of  the  oil  was  excellent.  There- 
fore, there  is  some  doubt  as  to  the  truth  of  the  statement  that  redis- 
solved solid  fats  impart  a  "tallowy"  taste. 

In  northern  Africa  it  is  stated  by  Chappelle  and  Kuby  (see  refer- 
ence, page  43)  that  some  of  the  oil  is  artificially  chilled  to  cause 
separation  of  the  solid  fats  and  is  then  filter  pressed  to  remove  them 
from  the  oil.  Oil  from  olives  grown  in  very  hot  districts,  according 
to  Bonnet,  contain  much  more  stearin  than  those  grown  in  cooler 
climates — this  explains  the  difference  in  treatment  in  southern  Europe 
and  northern  Africa. 

5.  Oil  Standards. — In  Spain,  the  writer  was  informed  by  Dr. 
Aguilo,  Director  of  the  Olive  Oil  Station  and  Laboratory  of  Tortosa, 
three  general  grades  of  oil  are  recognized  in  the  Spanish  trade :  fine  oil 
("aceite  fino")  containing  less  than  1%  per  cent  of  free  fatty  acid 
and  of  fine  flavor  and  odor;  common  oil  ("aceite  corriente")  with  less 
than  5  per  cent  of  free  fatty  acid  and  of  fair  quality,  and  sub-standard 
oil  with  more  than  5  per  cent  of  free  fatty  acid  or  oil  below  this 


Circular  279] 


OLIVE    OIL    IN    SOUTHERN    EUROPE 


33 


acidity,  but  otherwise  unsuitable  for  food  purposes  on  account  of 
objectionable  flavor  or  odor.  The  sub-standard  oil  can  often  be 
refined  and  blended  with  better  oils — as  a  matter  of  fact,  this  is  very 
common  practice.  Oil  from  olives  badty  infested  with  the  larvae  of 
the  olive  fly  is  usually  sub-standard  and  may  often  contain  15  to  20 
per  cent  of  free  fatty  acid,  making  it  fit  only  for  soap  stock.  Oil 
extracted  from  the  pomace  with  carbon  bisulfid  or  other  solvent  is 
also  sub-standard  and  usually  suitable  only  for  soap  stock. 


Fig.  24. — French  upright  type  olive  oil  filter  press  using  paper  discs. 


Olive  oil  is  bought  and  sold  on  analysis  as  well  as  on  flavor  and 
odor.  The  refiners,  who  are  also  the  principal  dealers,  pay  the  oil 
manufacturer  according  to  the  acidity  of  the  oil — the  price  rapidly 
decreasing  as  the  acidity  increases.  Color  standards  are  also  observed 
in  the  refineries,  and  the  final  products  so  adjusted  by  refining  and 
blending  that  an  oil  of  a  given  grade  will  be  uniform  in  color  from 
year  to  year. 


34  UNIVERSITY    OF    CALIFORNIA EXPERIMENT   STATION 

Calif  or  nian  oil  makers  should  adopt  standards  of  acidity  and 
color — there  is  altogether  too  much  variation  in  these  respects  in  our 
oils  at  present.     The  acidity  is  easily  determined  as  follows : 

Place  50  c.c.  of  alcohol  in  a  beaker  (denatured  alcohol  will  do).  Add  a  few- 
drops  of  phenolphthelein  indicator.  From  a  burette  add,  drop  by  drop,  barely 
enough  tenth  normal  sodium  hydroxide  to  cause  the  color  to  become  permanently 
pink.  With  a  clean  pipette  add  10  c.c.  of  oil  and  stir  with  a  glass  rod  to 
dissolve.  Take  reading  on  the  burette  containing  the  tenth  normal  sodium 
hydroxide.  Add  the  hydroxide  solution  slowly  at  first,  and  finally  very  slowly, 
drop  by  drop,  constantly  stirring  with  a  glass  rod,  until  a,  permanent  pink  color 
is  obtained.  Eead  the  burette.  Subtract  the  first  reading  from  the  second.  The 
difference  is  the  amount  of  sodium  hydroxide  in  cubic  centimeters  used  to 
neutralize  the  oil.  Multiply  this  figure  by  0.282.  The  result  will  be  " grams  of 
free  fatty  acid  per  100  cubic  centimeters  (300  c.c.)  of  oil"  and  is  usually 
understood  as  "per  cent."  To  obtain  actual  per  cent,  that  is  grams  of  free 
fatty  acid  per  100  grams  of  oil,  multiply  the  " grams  per  100  c.c."  by  1.3. 

A  good  oil  should  contain  less  than  1.5  per  cent  free  fatty  acid. 

Doubtful  samples  should  be  submitted  to  a  reliable  commercial 
analyst. 

6.  Packaging. — Olive  oil,  both  crude  and  refined,  is  transported  in 
steel  drums  such  as  are  used  in  America  for  gasoline  and  engine 
distillate.  Apparently  tin  is  not  essential.  Wooden  barrels  are  also 
used. 

In  the  large  oil  refineries  cans  are  made  and  lithographed  on  the 
premises  from  sheet  tin  imported  from  England  or  northern  Spain. 
The  large  can  factories  such  as  exist  in  America  are  not  common  in 
European  countries. 

The  oil  is  filtered  just  before  canning  or  bottling  in  order  to  give 
it  a  ''polish,"  that  is,  to  make  it  brilliantly  clear.  The  acidity  of 
canned  oil  must  be  low  in  order  to  avoid  action  on  the  metal  with 
consequent  development  of  a  green  color.  Cans  are  filled  by  weight 
and  bottles  to  a  uniform  height.  Great  care  is  taken  to  see  that  the 
containers  are  thoroughly  dry  when  filled.  Moisture  causes  cloudiness 
and  spoiling. 

"Sulfur  oil"  (by-product  olive  oil)  is  exported  in  steel  drums  or 
in  wooden  barrels,  table  oils  in  smaller  containers  of  tin  or  glass. 

EEFINING  TPTE  OIL 

The  refining  and  blending  of  olive  oil  has  become  a  very  important 
industry  in  Spain,  France,  and  Italy.  Many  olive  oils  require  refining 
before  they  can  be  used  for  food — many  others  of  edible  quality  are 
greatly  improved  by  refining.  Marseilles  in  France,  Seville,  Cordoba, 
and  Reus  in  Spain,  and  Genoa  in  Italy  are  important  refining  centers. 


Circular  279]  olive   oil   in   SOUTHERN   EUROPE  35 

Refining  consists  in  removing  excessive  free  fatty  acid,  excessive 
color  and  objectionable  odors  and  tastes.  Methods  vary  somewhat  in 
the  different  refineries,  but  the  basic  principles  applied  are  the  same 
in  all. 

1.  Deacidifieation. — The  removal  of  the  excess  of  free  fatty  acid  is 
the  first  treatment.  The  acidity  of  the  oil  is  determined  by  titration. 
A  measured  volume  of  oil  is  placed  in  the  neutralizing  tank,  which 
in  the  factories  visited  consists  of  a  steam-jacketed,  tin-lined,  steel 
tank  of  cylindrical  shape  and  fitted  with  an  agitator.  The  agitator  in 
one  instance  was  a  small  propellor  similar  to  those  used  on  small 
motor  boats.  This  was  placed  at  one  side  and  near  the  bottom  of  the 
tank. 

To  the  oil  is  added  the  amount  of  sodium  hydroxide  solution  (soda 
lye)  found  necessary  by  analysis,  to  neutralize  the  free  fatty  acid  of 
the  oil.  According  to  Dr.  Fachini,  Chief  of  the  Oil  School  of  Milan 
University,  Italy,  a  lye  solution  of  17°  Baume  is  suitable.  A  refiner 
stated  that  the  lye  solution  used  in  his  refinery  is  12°  Baume.  To 
neutralize  1  per  cent  of  free  fatty  acid  (1  gram  per  100  c.c.)  there 
would  be  required  1  gallon  of  lye  solution  of  12°  Baume  or  %  gallon 
of  17°  Baume  for  100  gallons  of  oil.  Other  acidities  would  require 
lye  in  proportion.  If  the  lye  solution  is  too  dilute  a  troublesome 
emulsion  will  form. 

The  mixture  is  stirred  and  heated  until  reaction  is  complete. 
According  to  Dr.  Fachini  the  temperature  should  reach  about  165°  F. 

The  free  fatty  acid  and  lye  combine  to  form  soap.  This  being 
heavier  than  the  oil  settles  out  and  can  be  separated  by  settling  and 
drawing  off.  The  settling  takes  place  in  tanks  with  conical  bottoms. 
Filtration  is  necessary  if  the  settling  is  not  complete. 

2.  Removal  of  Excess  of  Color. — This  follows  deacidification. 
Fuller's  earth  is  used  in  most  refineries,  although  in  a  Spanish 
refinery  visited  in  Seville,  decolorizing  carbon,  presumably  boneblack, 
was  used.  Finely  ground  fuller's  earth  or  finely  ground  vegetable 
or  animal  charcoal  is  mixed  with  the  oil  and  the  oil  heated  and  stirred 
in  a  steam-jacketed  tin-lined  tank.  The  amount  of  decolorizing  agent 
required  varies  greatly  according  to  the  depth  of  color  and  degree  of 
decolorizing  required.  In  experiments  in  the  Fruit  Products  Labora- 
tory 1  to  3  per  cent  by  weight  gave  satisfactory  results. 

The  length  of  treatment  was  not  learned  but  in  experiments  in  the 
laboratory  most  of  the  decolorizing  effect  was  obtained  by  one  hour's 
heating  at  160°  F. ;  very  little  additional  action  was  obtained  by 
heating  longer. 


36  UNIVERSITY   OF    CALIFORNIA — EXPERIMENT   STATION 

The  hot  oil  is  filtered  in  plate  and  frame  filter  presses  through 
canvas.  The  press  cake  may  be  treated  with  a  solvent  to  recover  the 
residual  oil. 

3.  Deodorizing. — The  oil  is  now  practically  free  from  fatty  acid 
and  usually  almost  water  white  in  color,  but  often  of  disagreeable  odor. 
It  is  well  known  that  superheated  steam  passed  through  an  odoriferous 
oil  will  volatize  the  odor  producing  compounds.  If,  however,  this  is 
conducted  at  atmospheric  pressure,  the  high  temperature  attained, 
together  with  the  moisture,  will  "crack"  the  oil,  that  is,  cause  for- 
mation of  glycerine  and  free  fatty  acid.  The  flavor  aLso  will  be 
injured. 

But  if  the  oil  is  placed  under  a  high  vacuum  and  superheated 
steam  is  passed  through  it,  the  temperature  remains  low,  e.g.,  150°  F. 
or  less,  because  the  steam  expands  tremendously  in  the  vacuum  and 
therefore  drops  in  temperature.  Consequently,  there  is  little  injurious 
effect  of  heat.  At  the  same  time  the  volatility  of  the  odorous  com- 
pounds is  greatly  increased  and  these  are  carried  off,  practically 
completely,  by  the  steam. 

The  deodorizers  seen  and  those  described  and  sketched  for  me  by 
Ed.  Battaile  &  Co.  of  Paris  consist,  first,  of  a  steam- jacketed  vacuum 
pan,  presumably  tin  lined.  This  is  connected  to  a  barometric  con- 
denser and  high  duty,  dry-vacuum  pump.  The  second  feature  is  the 
steam  supply.  Steam  is  passed  through  a  superheater  placed  near 
the  vacuum  pan.  This  is  merely  a  pipe  surrounded  by  a  jacket  con- 
taining high  pressure  steam.  Superheating  increases  the  temperature 
of  the  steam  above  that  at  its  saturation  point.  It,  therefore,  enters 
the  vacuum  pan  in  a  "dry"  state,  free  of  condensed  vapor.  It  also,  if 
superheated,  expands  to  a  greater  volume  in  the  vacuum  pan  than 
would  otherwise  be  the  case  and  thereby  exerts  greater  effect  on 
removal  of  volatile  odors.  The  steam  passes  into  the  condenser,  where 
a  spray  of  water  condenses  it  to  water,  which  overflows  from  the  con- 
densate tank  at  the  foot  of  the  barometric  condenser.  The  vacuum 
pump  removes  air  and  other  gases  and  should  maintain  a  vacuum  of 
27-28%  inches. 

4.  Refining  Experiments  in  Fruit  Products  Laboratory. — Four 
one-quart  samples  of  rancid,  odoriferous  oil  were  treated  in  glass  flasks 
by  the  foregoing  processes  of  deacidification,  decolorizing,  and  de- 
odorization  by  steam  in  vacuo.  Deacidification  was  conducted  with 
calculated  amounts  of  10  per  cent  sodium  hydroxide  solution. 
Decolorizing  was  accomplished  by  heating  with  2  per  cent  by  weight 
of  Darco  vegetable  decolorizing  carbon.     The  treated  oil  was  filtered 


Circular  279]  olive   oil   IN   SOUTHERN   EUROPE  37 

through  paper  after  addition  to  the  oil  of  1  per  cent  by  weight  of 
"Filter-Cel."  The  deaciclified,  decolorized  sample  was  placed  in  a 
flask;  a  vacuum  of  28  inches  applied  and  steam  passed  through  at 
160°  F.  The  steam  was  not  superheated,  hence  did  not  exert  as  high 
deodorizing  power  as  could  be  obtained  by  superheating.  Nevertheless, 
three  of  the  samples  were  deodorized  sufficiently  by  15  minutes'  treat- 
ment— the  fourth  retained  some  of  its  objectionale  odor  after  15 
minutes'  steam  treatment,  although  greatly  improved. 


UTILIZING  THE  BY-PEODUCTS 

The  principal  by-products  from  olive  oil  factories  is  the  pomace 
(press  cake).  Of  less  importance  are  the  foots  (settlings  from 
storage  tanks)  and  the  "black  liquor"  or  juice  from  the  oil  and  juice 
separators. 

1.  Oil  from  Pomace. — The  pomace  from  efficient  presses  contains 
only  8  per  cent  or  less  of  oil ;  imperfectly  pressed  pomace  may  contain 
12  per  cent  or  more.  As  described  elsewhere,  page  23,  the  pomace  may 
be  ground  in  water  by  an  edge  runner  and  2  to  5  per  cent  of  oil 
recovered  by  flotation  in  water.  Much  higher  yields  are  obtained  by 
drying  the  pomace  and  extracting  it  with  a  volatile  solvent. 

The  solvent  most  commonly  used  is  carbon  bisulfide.  This  is  a 
volatile,  very  inflammable  liquid,  heavier  than  water,  and  possessing 
high  oil  solvent  properties. 

Benzol,  a  volatile  liquid  obtained  as  a  by-product  from  coke  ovens 
and  gas  plants,  is  also  used.  It  is  less  volatile  and  therefore  less 
dangerous  than  carbon  bisulfide,  but  more  costly. 

Gasoline  and  benzine  are  also  used  successfully. 

Recently  a  non-inflammable  solvent,  trichlorethylene,  known  in 
commerce  as  ' ' trielene ' '  has  come  into  use  in  France  through  the  work 
of  J.  Bonnet,  Director  of  the  Olive  Service. 

It  is  possible  to  completely  remove  any  of  the  above  solvents  from 
the  oil  by  distillation,  to  recover  most  of  the  solvent  followed  by  treat- 
ment of  the  residual  oil  in  vacuo  with  superheated  steam  as  in  refining. 
If  the  pomace  is  treated  fresh,  within  a  day  or  two  after  pressing,  an 
edible  oil  containing  less  than  5  per  cent  free  f atty  acid  can  be  obtained. 
The  pomace  should  therefore  be  delivered  to  the  extractor  as  soon  as 
possible.  If  more  pomace  is  delivered  than  the  extractor  can  care  for, 
the  excess  should  be  dried  and  held  until  the  end  of  the  season  and 
the  extractor  operated  to  capacity  on  fresh  pomace  in  order  to  obtain 
the  maximum  of  oil  of  low  acidity. 


38  UNIVERSITY    OF    CALIFORNIA EXPERIMENT   STATION 

Drying  was  accomplished  in  one  factory  visited  in  France  by  con- 
ducting the  ground  pomace  by  means  of  a  screw  conveyor  through  an 
open  steam-jacketed  metal  trough.  In  a  large  refinery  in  Spain  dry- 
ing was  done  in  a  rotating  metal  drum  through  which  passed  a  blast 
of  hot  air.  Inexpensive  drying  methods  must  be  used  as  the  product 
is  of  low  value.  In  another  plant  the  pomace  was  spread  in  the  sun 
or  on  a  concrete  floor  to  air  dry.  This  method  is  slow  and  permits 
molding,  souring,  and  rancidification.  Artificial  heat  is  therefore  to 
be  preferred. 

The  extractor  observed  in  a  Spanish  factory  consisted  of  the  fol- 
lowing parts:  (a)  an  extracting  tank,  (b)  still,  (c)  condenser,  and 
(d)  reservoir.  The  dried  pomace  was  placed  in  the  extracting  tank 
which  was  then  filled  with  solvent  from  the  reservoir.  This  was 
allowed  to  remain  a  short  time  and  was  then  drawn  off  into  the  still. 
Here  it  was  volatalized  and  condensed  above  the  extracting  tank  into 
which  it  flowed,  dissolved  for  more  oil,  and  returned  to  the  still.  This 
cycle  was  continued  until  the  pomace  was  practically  exhausted  of 
oil.  Steam  was  then  turned  into  the  pomace  in  the  extractor  and  most 
of  the  remaining  solvent  recovered  by  distillation.  Carbon  bisulfide 
was  used  as  a  solvent, 

The  extractor  seen  in  an  oil  factory  in  Nimes,  France,  was  operated 
in  a  similar  manner,  except  that  tricblorethylene  was  used  as  a  solvent. 
This  solvent  boils  at  86-87°  C.  (186.8-188.6°  F.).  Since  trichlore- 
thylene is  non-inflammable  and  less  volatile  than  carbon  bisulfide,  it  is 
a  very  suitable  solvent.  Although  it  is  higher  in  price  than  most  other 
commercially  used  solvents,  the  amount  lost  in  operation  is  not  so 
great  that  the  price  is  prohibitive.  According  to  J.  Bonnet,  about 
1.3  gallons  is  lost  per  ton  of  pomace.  According  to  Batataile  &  Co., 
manufacturers  of  solvent  equipment,  in  Paris,  about  1.5  gallons  is  lost 
per  ton. 

At  the  time  of  the  writer 's  visit  the  price  for  this  ' '  trielene ' '  was 
given  by  Mr.  Bonnet  at  2.5  francs  per  kilogram,  or  about  61/2C  per 
pound  or  about  45c  per  gallon.  With  pomace  containing  8  per  cent  of  oil 
on  the  wet  basis — about  12  per  cent  on  the  dry  basis — and  a  recovery 
of  10  per  cent  on  the  dry  basis,  the  yield  of  oil  would  be  200  pounds 
per  dry  ton  or  about  27  gallons.  The  cost  of  the  solvent  would  then 
be,  if  2  gallons  per  ton  were  lost  (%  gallon  more  than  Battaile  Co. 's 
estimate)  90c  per  ton  or  about  31/>c  per  gallon  of  oil  recovered.  To 
this,  of  course,  must  be  added  the  cost  of  handling,  interest  on  invest- 
ment, depreciation,  etc.  Experience  at  Nimes,  according  to  J.  Bonnet, 
has  shown  these  costs,  plus  cost  of  solvent  lost,  to  be  about  220  francs 


CIRCULAR  279]  OLIVE    OIL    IN    SOUTHERN    EUROPE  39 

per  4000  kilograms  of  pomace  or  about  $2.50  per  ton  of  pomace.  This 
plant  has  a  capacity  of  4.4  tons  of  pomace  per  day. 

The  equipment  need  not  be  expensive  if  made  from  galvanized 
sheet  metal  and  iron  steam  pipe.  In  fact  any  sheet  metal  shop  could 
make  up  a  simple  outfit  from  published  sketches  and  descriptions. 

Possibly  one  such  plant  in  each  of  the  important  oil  districts  of 
the  state  would  be  profitable. 

2.  Pomace  for  Stock  Feed. — Extracted  pomace  is  not  suitable  for 
stock  feed.  Fresh  pomace,  according  to  Professor  Mantons,  taken 
before  it  has  molded  or  soured  may  be  put  through  a  machine  consist- 
ing of  a  disintegrator,  screen  and  fan,  which  separates  the  pits  from 
the  skins  and  pulp.  The  pulp  is  a  fairly  good  stock  feed  and  the  pits 
may  be  used  as  fuel  or  may  be  distilled  to  give  charcoal,  wood  alcohol, 
and  acetic  acid. 

3.  Use  of  Black  Liquor. — The  juice  from  the  separating  tanks,  or 
centrifugals  is  usually  discarded.  In  one  large  factory,  however.  I 
was  told  that  this  juice  is  allowed  to  stand  in  shallow  open  air  vats. 
Some  oil  is  recovered  by  skimming  and  the  juice  evaporates,  leaving 
a  residue  with  considerable  fertilizing  value.  This  treatment  can  be 
given  only  in  semi-arid  districts. 

4.  Foots. — The  foots,  settlings  from  the  oil  storage  tanks,  as  in 
California  is  sold  for  soap  stock. 

SUMMARY  AND   CONCLUSIONS 

1.  Olive  oil  is  a  staple  food  in  southern  Europe  and  its  manu- 
facture a  basic  food  industry.  The  situation  in  California  is  different 
in  these  respects.  Here  olives  are  grown  principally  for  pickling,  the 
production  of  a  luxury. 

2.  The  total  acreage  of  olives  in  France,  Greece,  Italy,  Portugal, 
Spain,  Algeria,  and  Tunis  in  1922  was  over  11,750,000,  according  to 
Dore  of  the  International  Institute  of  Agriculture  of  Rome.  If 
Turkey,  Palestine,  etc.,  are  included  the  total  would  exceed  12,000,000 
acres.  Italy  leads  with  5,659,000  acres,  and  Spain  is  second  with 
4,102,000  acres,  according  to  Dore's  report. 

3.  Production  in  individual  countries  varies  greatly  from  year 
to  year,  but  for  the  Mediterranean  region  as  a  whole  has  been  fairly 
constant  from  1911  to  1922,  inclusive.  It  is,  therefore,  advisable  to 
discount  reports  made  before  harvest  of  crop  shortages  or  abnormally 
large  crops  in  various  Mediterranean  countries. 


40  UNIVERSITY    OF    CALIFORNIA — EXPERIMENT   STATION 

4.  The  Spanish  olive  oil  industry  was  not  prosperous  at  the  time  of 
the  writer's  visit,  because  of  poor  export  demand  occasioned  by  un- 
favorable exchange  rates  between  Spain  and  Italy  and  France,  and  by 
the  Spanish  Government's  embargo  on  the  export  of  olive  oil  during 
the  last  year  of  the  World  War.  The  embargo  prevented  Spain's 
retaining  her  export  market  developed  during  the  war.  France  and 
Italy  still  import  Spanish  oil  for  blending  purposes,  although  increas- 
ing quantities  are  now  imported  from  northern  Africa.  In  France  and 
Italy  the  oil  industry  appeared  to  be  in  a  much  better  economical 
condition;  nevertheless  the  cost  of  production  of  oil  has  risen  out  of 
proportion  to  the  returns. 

5.  Many  cooperative  oil  factories  are  in  successful  operation  and 
are  being  built  in  Spain  and  France.  These  are  replacing  the 
numerous  individual  farm  mills.  The  oil  made  in  the  cooperative 
plants  is  much  better  than  that  made  in  the  antiquated,  unsanitary 
farm  outfits.  The  respective  governments  are  furnishing  every 
possible  aid  to  these  cooperatives. 

6.  According  to  a  recent  report  of  the  Spanish  Department  of  the 
Interior,  the  average  cost  of  producing  oil,  including  the  cost  of 
the  olives,  was,  for  eight  leading  oil  producing  provinces,  $.736 
(American)  per  gallon.  In  France  it  is  probably  about  equal  to  the 
Spanish  cost;  in  Italy  it  is  less. 

7.  The  growing  of  olives  for  oil  is  similar  to  that  for  pickles  as 
described  in  Circular  278  of  this  Station.  However,  pruning  of  oil 
olive  trees  in  Spain  is  less  severe  and  the  orchards  are  given  less  care 
because  of  the  smaller  financial  returns  from  oil  olives. 

8.  In  southern  Spain  the  Zorzalena  (probably  the  same  as  the 
Nevadillo)  is  the  most  important  variety  of  oil  olive;  in  northern 
Spain  the  Arbequina.  In  France  dual  purpose  olives  are  grown  to 
a  greater  extent  than  in  Spain  or  Italy;  thus  the  Picholine  and 
Verdal  are  planted  extensively  for  both  pickling  and  for  oil.  Perhaps 
the  Picholine  or  some  other  variety  suitable  for  both  pickling  and  oil 
making  would  prove  desirable  in  California  for  similar  use.  In  Italy 
the  varieties  are  multitudinous  in  number. 

9.  Harvesting  olives  for  oil  is  done  less  carefully  than  in  Cali- 
fornia, the  fruit  usually  being  knocked  or  stripped  from  the  trees  on 
to  the  ground  or  on  to  sheets.  All  European  authorities  agree,  how- 
ever, that  hand  picking  from  the  tree  is  greatly  to  be  preferred  to 
other  methods. 

10.  The  olives  are  usually  transported  in  sacks,  in  which  sweating, 
heating,  and  fermentation  frequently  occur.     Baskets  are  preferable. 


Circular  279]  OLIVE  OTL   IN   SOUTHERN   EUROPE  41 

11.  Storage  of  the  olives  in  deep  bins  was  at  one  time  a  common 
practice  but  is  being  replaced  by  storage  in  shallow  piles  and  frequent 
stirring  to  minimize  decomposition  before  pressing.  Pressing  within 
twenty-four  hours  after  harvest  is  the  best  practice,  and  is  followed  in 
the  best  Spanish  factories. 

12.  The  olive  fly  is  a  serious  pest  in  several  oil  districts,  particu- 
larly in  the  Tarragona-Tortosa  district  of  Spain  and  in  Tuscany  in 
Italy.  Over  90  per  cent  of  the  fruit  becomes  infested  in  some  seasons, 
so  injuring  the  quality  of  much  of  the  oil  that  it  must  be  used  for 
by-product  purposes.  The  infestation  of  oil  olives  is  more  severe  than 
that  of  pickling  olives  because  the  former  hang  on  the  tree  one  to 
three  months  longer. 

13.  Crushing  and  pressing  equipment  and  methods  are  not  radi- 
cally different  from  those  in  California.  In  France  only  two  pressings, 
and  without  removal  of  the  pulp  from  the  press  cloths,  are  given — the 
second  pressing  being  at  higher  pressure  than  in  other  countries.  This 
method  reduces  labor  costs  and  equipment.  Several  new  methods  of 
oil  extraction  are  under  investigation.  Of  these  the  Acapulco  process 
seems  to  have  made'  the  most  progress.  It  consists  in  separating  the 
oil  from  the  pulp  and  water  by  rubbing  the  finely  ground  pulp  against 
a  very  fine  nickel  screen.  A  continuous  press  (the  Colin)  also  is  said 
to  give  good  results.  Probably  modifications  of  one  or  more  of  these 
new  methods  would  be  useful  in  California  as  a  means  of  reducing 
costs  and  increasing  yields  and  perhaps  quality. 

14.  Centrifugal  separation  of  oil  and  ' '  black  liquor ' '  has  come  into 
general  use  in  France  as  a  substitute  for  settling  and  decantation  or 
skimming.    The  new  method  is  spreading  also  to  Spain  and  Italy. 

15.  Oil  is  not  washed  to  the  extent  practiced  in  California.  Spanish 
oil  makers  prefer  not  to  wash  the  oil  at  all,  but  to  remove  bitterness 
by  long  storage,  settling,  and  racking.  Washing  removes  desirable 
odors  and  flavors. 

16.  Demargination  is  not  practiced  except  in  northern  Africa  for 
oils  very  rich  in  solid  fats. 

17.  Glass  lined  or  glazed  tile  lined  tanks  are  preferred  for  storage, 
although  tin  lined  tanks  and  large  earthen  jars  are  in  common  use  in 
small  factories. 

18.  Filters  are  usually  of  the  filter  press  type — these  use  cloth  in 
some  cases,  although  the  apparently  most  popular  filter  press  uses 
discs  of  specially  prepared  paper.  The  funnel  and  paper  filter  is  con- 
demned because  it  exposes  a  large  surface  to  oxidation,  permits  undue 
loss  of  flavor  and  aroma,  and  exposes  the  oil  to  the  danger  of  con- 


42  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

lamination  by  foreign  odors.    California  oil  makers  should  investigate 
and  try  the  European  methods  of  nitration. 

19.  Much  oil  is  refined  in  large,  centrally  located  refineries  in 
Seville,  Reus,  Marseilles,  Genoa,  and  elsewhere.  Oil  that  would  other- 
wise be  inedible  because  of  high  acidity  or  disagreeable  flavor  and 
odor  is  made  by  refining  into  a  light  colored,  mild  oil  suitable  for 
blending  purposes.  Refining  usually  consists  in  neutralizing  the  free 
acid  by  a  sodium  hydroxide  solution  (soda  lye),  removing  excess  of 
color  with  fuller's  earth  or  decolorizing  carbon,  and  deodorizing  by 
treatment  with  superheated  steam  in  vacuo.  Part  of  this  process, 
deacidification  and  decolorizing,  can  be  accomplished  in  Calif ornian 
factories  with  the  present  equipment;  deodorization  would  require 
special  equipment,  although  this  need  not  be  very  expensive. 

20.  The  pomace  is  utilized  throughout  the  olive  oil  region  of  the 
Mediterranean  for  the  recovery  of  the  residual  oil.  Solvent  treating 
plants  purchase  the  pomace  at  prices  remunerative  to  the  oil  factories 
or  the  larger  factories  operate  their  own  solvent  plants.  Carbon 
bisulfide  is  the  usual  solvent,  but  trichlorethylene  is  coming  into  use 
because  of  its  non-inflammability.  A  dry  ton  of  California  pomace 
should  yield  at  least  25  gallons  of  oil  or  a  fresh  ton  20  gallons  by 
solvent  extraction.  At  50c  a  gallon  this  would  return  $10  to  $12.50 
a  ton.  The  extracted  pomace  would  still  be  suitable  for  fuel.  Whether 
the  treatment  of  the  pomace  would  prove  profitable  in  California  is 
an  open  question.     It  is  at  least  worthy  of  investigation. 

21.  Olive  oil  is  bought  and  sold  in  Europe  on  definite  standards. 
Free  fatty  acid  is  the  most  important  basis  of  judgment  of  quality — 
color  is  also  very  important.  California  oil  manufacturers  would  do 
well  to  adopt  definite  standards  for  color  and  free  fatty  acid  in  order 
that  the  oil  would  have  a  more  definite  standing  in  the  trade. 


Circular  279]  OLIVE   OIL   IN   SOUTHERN    EUROPE  43 


LIST  OF  SELECTED  REFERENCES 

i  El  Comercio  de  Aceites  en  Espafia,  by  L.  A.  Lamarca.  Published  by  Libreria 
Calpe,  Madrid. 

2  El  Aeeite  de  Oliva,  Resumen  hecbo  por  la  Junta  Consultiva  Agronomica  de 

Madrid,  1923.      Printed  and   obtainable  from  Los  Hijos  de  M.  C.  Her- 
nandez, Libertad  16,  Madrid,  Spain.     Cost  about  $3.00. 

3  Boletin  Mensual  de  Olivicultura.     Published  monthly  by  Don  Isidoro  Aguilo, 

Jefe  de  Estaeion  Olivera,  Tortosa,  Spain. 

4  P.  d 'Aygalliers,  L 'Olivier  et  l'Huile  d 'Olive.     Published  by  J.  B.  Bailliere 

et  Fils,  19  Rue  Haute  Feuille,  Paris.     Price,  50  francs  plus  postage;  total 
about  $3.00.     An  excellent  book, 
s  J.  Bonnet,  L'Olivier.      (1924.)     The  same  publisher  and  price  as  reference 
No.  4.     An  excellent  book  and  up  to  date. 

6  J.  Chappelle  and  J.  Ruby.    l'Huilerie  Moderne.     Published  by  Librerie  Poly- 

technique,  15  rue  Saints-Peres,  Paris.     Out  of  print.     The  best  book  in 
French  on  oil. 

7  Les  Matieres  Grasses.     Monthly  journal  on  oils.     Published  by  A.  D.  Gillard, 

Les  Matieres  Grasses,  49  rue  de  Yinaigriers,  Paris.     Price,  36  francs  per 
annum.     About  $2.10. 

s  La  Revue  Oleicole,  published  monthly.  71  rue  de  la  Procession,  Paris.  Price, 
15  francs  per  annum  plus  postage;  total  about  $1.25.  Covers  olives  and 
oil. 

» Dore,  Valentino.  Oleaginous  Products  and  Vegetable  Oils.  (Statistical.) 
Published  by  the  International  Institute  of  Agriculture,  Villa  Borghesi, 
Rome.  (1923.)  Very  good.  Price  not  known  but  probably  less  than 
$2.50. 

io  L'Industria  degli  Olii  e  dei  Grassi  (Italian).  Published  by  Dottore  S.  Fachini, 
R.  Laboratoria  Olii  e  Grassi,  Via  Marina  5,  Milan,  Italy.  Postpaid,  60 
lira  per  annum  ($3.00.)     Published  monthly. 

ii  A.  Cravino  and  A.  Zuccarello.  Come  produrre  dell 'olio  migliore  nel  Meridi- 
onale.     10  lira  (50c).     Fratolli  Ottari,  Casale,  Montferrat,  Italy. 


STATION  PUBLICATIONS  AVAILABLE  FOR  FREE  DISTRIBUTION 


BULLETINS 
No.  No. 

253.   Irrigation   and   Soil  Conditions   in  the  346. 

Sierra  Nevada  Foothills,  California.  347. 

261.  Melaxuma    of    the    Walnut,    "Juglans 

regia."  348. 

262.  Citrus   Diseases   of   Florida   and  Cuba  349. 

Compared  with  Those  of  California. 

263.  Size  Grades  for  Ripe  Olives.  350. 
268.  Growing  and  Grafting  Olive  Seedlings.  351. 
273.   Preliminary  Report  on  Kearney  Vine-  352. 

yard  Experimental  Drain. 

275.  The  Cultivation  of  Belladonna  in  Cali-  353. 

fornia.  354. 

276.  The  Pomegranate.  357. 

277.  Sudan  Grass 

278.  Grain   Sorghums. 

279.  Irrigation  of  Rice  in  California.  358. 

280.  Irrigation  of  Alfalfa  in  the  Sacramento 

Valley.  359. 

283.  The  Olive  Insects  of  California.  360. 

285.  The  Milk  Goat  in  California. 

286.  Commercial  Fertilizers.  361. 

287.  Vinegar  from  Waste  Fruits. 

294.   Bean  Culture  in  California.  362. 

298.  Seedless  Raisin  Grapes.  363. 

304.  A  Study  of  the  Effects  of  Freezes  on 

Citrus   in   California.  364. 

310.  Plum  Pollination. 

312.  Mariout  Barley.  366. 

313.  Pruning  Young  Deciduous  Fruit  Trees. 

317.   Selections  of  Stocks  in  Citrus  Propa-  367. 

gation. 
319.   Caprifigs  and  Caprification.  368. 

321.   Commercial  Production  of  Grape  Syrup. 

324.  Storage  of  Perishable  Fruit  at  Freezing  369. 

Temperatures.  370. 

325.  Rice  Irrigation  Measurements  and  Ex-  371. 

periments     in     Sacramento     Valley, 
1914-1919.  372. 

328.  Prune  Growing  in  California. 

331.   Phylloxera-Resistant  Stocks.  373. 

334.  Preliminary  Volume  Tables  for  Second-  374. 

Growth  Redwood. 

335.  Cocoanut  Meal   as   a   Feed  for  Dairy 

Cows  and  Other  Livestock.  375. 

336.  The   Preparation  of   Nicotine  Dust  as 

an  Insecticide.  376. 

339.  The  Relative  Cost  of  Making  Logs  from 

Small  and  Large  Timber.  377. 

340.  Contrel  of  the  Pocket  Gopher  in  Cali-  378. 

fornia. 

343.  Cheese  Pests  and  Their  Control. 

344.  Cold  Storage  as  an  Aid  to  the  Market- 

ing of  Plums. 


Almond  Pollination. 

The  Control  of  Red  Spiders  in  Decidu- 
ous Orchards. 

Pruning  Young  Olive  Trees. 

A  Study  of  Sidedraft  and  Tractor 
Hitches. 

Agriculture  in  Cut-over  Redwood  Lands. 

California  State  Dairy  Cow  Competition. 

Further  Experiments  in  Plum  Pollina 
tion. 

Bovine  Infectious  Abortion. 

Results  of  Rice  Experiments  in   1922. 

A  Self-mixing  Dusting  Machine  for 
Applying  Dry  Insecticides  and 
Fungicides. 

Black  Measles,  Water  Berries,  and 
Related  Vine  Troubles. 

Fruit  Beverage  Investigations. 

Gum  Diseases  of  Citrus  Trees  in  Cali- 
fornia. 

Preliminary  Yield  Tables  for  Second 
Growth  Redwood. 

Dust  and  the  Tractor  Engine. 

The  Pruning  of  Citrus  Trees  in  Cali- 
fornia. 

Fungicidal  Dusts  for  the  Control  of 
Bunt. 

Turkish  Tobacco  Culture,  Curing  and 
Marketing. 

Methods  of  Harvesting  and  Irrigation 
in  Relation  to  Mouldy  Walnuts. 

Bacterial  Decomposition  of  Olives  dur- 
ing Pickling. 

Comparison  of  Woods  for  Butter  Boxes. 

Browning  of  Yellow  Newtown  Apples. 

The  Relative  Cost  of  Yarding  Small 
and  Large  Timber. 

The  Cost  of  Producing  Market  Milk  and 
Butterfat  on  246  California  Dairies. 

Pear  Pollination. 

A  Survey  of  Orchard  Practices  in  the 
Citrus  Industry  of  Southern  Cali- 
fornia. 

Results  of  Rice  Experiments  at  Cor- 
tena,    1923. 

Sun-Drying  and  Dehydration  of  Wal- 
nuts. 

The  Cold  Storage  of  Pears. 
Studies  on  the  Nutritional  Disease  of 
Poultry    Caused   by   Vitamin    A   De- 
ficiency. 


CIRCULARS 

No.  No. 

70.  Observations    on    the    Status    of    Corn  155. 

Growing  in  California.  157. 

87.  Alfalfa.  160. 

111.  The  Use  of  Lime  and  Gypsum  on  Cali-  161. 

fornia  Soils.  164. 

113.  Correspondence  Courses  in  Agriculture.  165. 
117.  The    Selection    and    Cost   of    a    Small 

Pumping  Plant.  166. 

127.   House  Fumigation.  167. 

129.  The  Control  of  Citrus  Insects.  170. 
136.  MeKlotus   indica    as    a    Green-Manure 

Crop  for  California.  172. 

144.    Oidium  or  Powdery  Mildew  of  the  Vine.  173. 

151.  Feeding  and  Management  of  Hogs. 

152.  Some  Observations  on  the  Bulk  Hand-  174. 

ling  of  Grain  in  California.  178. 

154.   Irrigation   Practice  in   Growing  Small  179. 
Fruit  in  California. 


Bovine  Tuberculosis. 

Control  of  the  Pear  Scab. 

Lettuce  Growing  in  California. 

Potatoes  in  California. 

Small  Fruit  Culture  in  California. 

Fundamentals   of   Sugar   Beet   Culture 

under  California  Conditions. 
The  County  Farm  Bureau. 
Feeding  Stuffs  of  Minor  Importance. 
Fertilizing  California  Soils  for  the  1918 

Crop. 
Wheat  Culture. 
The    Construction    of    the    Wood-Hoop 

Silo. 
Farm  Drainage  Methods. 
The  Packing  of  Apples  in  California. 
Factors    of    Importance    in    Producing 

Milk  of  Low  Bacterial  Count. 


CIRCULARS —  ( Continued  ) 


No. 

184. 

190. 

193. 

198. 

199. 

202. 

203. 

205. 
208. 

209. 
210. 
212. 
214. 

215. 

217. 

219. 

220. 
228. 
230. 

231. 
232. 

233. 
234. 

235. 

236. 


237. 


238. 
239. 


240. 
241. 


242. 
243. 


244. 


A  Flock  of  Sheep  on  the  Farm. 

Agriculture  Clubs  in  California. 

A  Study  of  Farm  Labor  in  California. 

Syrup  from  Sweet  Sorghum. 

Onion  Growing  in  California. 

County   Organizations   for   Rural   Fire 

Control. 
Peat  as  a  Manure  Substitute. 
Blackleg. 
Summary  of  the  Annual  Reports  of  the 

Farm  Advisors  of  California. 
The  Function  of  the  Farm  Bureau. 
Suggestions  to  the  Settler  in  California. 
Salvaging  Rain-Damaged  Prunes. 
Seed  Treatment  for  the  Prevention  of 

Cereal  Smuts. 
Feeding  Dairy  Cows  in  California. 
Methods   for   Marketing  Vegetables   in 

California. 
The  Present  Status  of  Alkali. 
Unfermented  Fruit  Juices. 
Vineyard  Irrigation  in  Arid  Climates. 
Testing   Milk,    Cream,    and   Skim  Milk 

for  Butterfat. 
The  Home  Vineyard. 
Harvesting    and    Handling    California 

Cherries  for  Eastern  Shipment. 
Artificial  Incubation. 
Winter  Injury  to  Young  Walnut  Trees 

during  1921-22. 
Soil  Analysis  and  Soil  and  Plant  Inter- 
relations. 

The  Common  Hawks  and  Owls  of  Cali- 
fornia   from    the    Standpoint   of    the 

Rancher. 
Directions  for  the  Tanning  and  Dress- 

of  Furs. 
The  Apricot  in  California. 
Harvesting  and  Handling  Apricots  and 

Plums  for  Eastern  Shipment. 
Harvesting    and    Handling    Pears    for 

Eastern  Shipment. 
Harvesting  and  Handling  Peaches  for 

Eastern   Shipment. 
Poultry  Feeding. 
Marmalade  Juice  and  Jelly  Juice  from 

Citrus  Fruits. 
Central  Wire  Bracing  for  Fruit  Trees. 


No. 
245. 
247. 
248. 

249. 
250. 

251. 


252. 
253. 
254. 

255. 

256. 
257. 
258. 
259. 
260. 

261. 
262. 
263. 
264. 

265. 
266. 

267. 

268. 

269. 
270. 
271. 
272. 

273. 
275. 

276. 

277. 

278. 


Vine  Pruning  Systems. 

Colonization  and  Rural  Development. 

Some  Common  Errors  in  Vine  Pruning 
and  Their  Remedies. 

Replacing  Missing  Vines. 

Measurement  of  Irrigation  Water  on 
the  Farm. 

Recommendations  Concerning  the  Com- 
mon Diseases  and  Parasites  of 
Poultry  in  California. 

Supports  for  Vines. 

Vineyard  Plans. 

The  Use  of  Artificial  Light  to  Increase 
Winter  Egg  Production. 

Leguminous  Plants  as  Organic  Fertil- 
izer in   California  Agriculture. 

The  Control  of  Wild  Morning  Glory. 

The  Small- Seeded  Horse  Bean. 

Thinning  Deciduous  Fruits. 

Pear  By-products. 

A  Selected  List  of  References  Relating 
to  Irrigation  in  California. 

Sewing  Grain   Sacks. 

Cabbage  Growing  in  California. 

Tomato  Production  in  California. 

Preliminary  Essentials  to  Bovine  Tuber- 
culosis Control. 

Plant  Disease  and  Pest  Control. 

Analyzing  the  Citrus  Orchard  by  Means 
of  Simple  Tree  Records. 

The  Tendency  of  Tractors  to  Rise  in 
Front;   Causes  and  Remedies. 

Inexpensive  Lavor-saving  Poultry  Ap- 
pliances. 

An  Orchard  Brush  Burner. 

A  Farm  Septic  Tank. 

Brooding  Chicks  Artificially. 

California  Farm  Tenancy  and  Methods 
of  Leasing. 

Saving  the  Gophered  Citrus  Tree. 

Marketable  California  Decorative 
Greens. 

Home  Canning. 

Head,  Cane,  and  Cordon  Pruning  of 
Vines. 

Olive  Pickling  in  Mediterranean  Coun- 
tries. 


15m-ll,'24 


